Yeah yeah so there's now a veritable cornucopia of would-be mac media center apps out there in their teaser, alpha and 1.0 version; all hoping to do what Front Row does but better.
I've finally gotten around to installing them all and gave them a test-drive over the past week.
Now keep in mind that none of them are really finished, polished pieces of work yet but there's enough meat here to review some of their most important features.
Ok let's back up for a minute, the uninitiated are asking "what's a mac media-center app?".
Good question (tho' god knows why you're asking that if you read this blog..)!
Media-center apps are basically all front-ends for accessing your media collection (music, video, photos, tv, DVDs, what-have-you) via a single unified interface. They all offer some kind of enlarged, simplified browsing interface suitable for viewing from a distance.
Which is nice because it's a total pain in the arse to have to squint at your TV to discern what's playing on iTunes, scroll through finder windows to find that movie you want to watch etc. etc. The mac interface just wasn't built for this task and hence the need for a media-center app to simplify and manage these tasks for you, ideally w./ the use of a remote control of some sort!
Ok onto our test subjects.
In order of completedness we have (drum roll please..):
Front Row (Apple)
MediaCentral (Equinox)
CenterStage (CenterStage Project)
iTheater (iTheater Project)
Now before we get into the nitty gritty of media file playback, interface, remote control integration here's a handy-dandy little matrix of feature-sets:

*Note: "x-" indicates either the app has plans to implement the feature in question but hasn't yet done so or that it's current implementation is buggy.
You'll notice there are some items in the table that aren't currently implemented by any of the media-center apps (i.e. iTunes server). I put them on the list because I think that in the end these features will become very important to a fully-functioning media-center app. I personally use a number of different software bits to kluge this functionality together when essentially it's all just media-management and playback with some networking thrown for good measure.
Just playing audio and video on your mac-tv via an enlarged interface is all well and good but for the mac-media-center of the future to really shine and take on new meaning for the consumer it will have to offer the ability to manage, browse and access your media collection from wherever you may be in your house or on the planet (ack!).
For example I currently have 160 gig + of music; nice to listen to at home but where it really becomes wondrous is when I can access that music collection while at work or at a friend's house w/ a broadband connection. Same goes for moving from one room to another. There's no reason why we shouldn't expect to be able to watch our video collection from any room in the house. You CAN do this right now w/ a collection of third party apps (see earlier posts on this blog) but it's not that easy to do and requires multiple different pieces of software to manage.
Ok enough preamble lets get to it!
Front Row
Hmm yeah so this is a special hacked version that *somehow* found it's way onto my sawtooth. Installation wasn't all that hard but you're mileage may vary, dramatically.
Interface:
Is clean and simple, works well from across the room and if you have a late gen iMac or MacBookPro you can control it with your IR remote.
It's not customizable though so if you want a different typeface or the ability to put in a background image of your choosing you're s.o.l.
What you see is what you get.
Media playback:
On my dual 1.3ghz G4 sawtooth the video, iTunes and movie previews played fine. I was in fact most impressed by how apple could get those movie previews to play back so smoothly, pause, rewind etc considering it was all streaming live across the net w/ out any pre-caching. My bandwidth is pretty good (cable) so your mileage may vary. iPhoto browsing caused it to crash every time but that's probably a function of cramming a piece of hacked software onto my ancient (1999!) sawtooth.
MediaCentral
Unlike some of the other media-center apps in this review MediaCentral is actually in release-ready shape (mostly).

Interface:
A simple scrolling interface (again no scroll-wheel support) allows you to choose what media you want to browse/play. Confusingly "-" lowers volume while "Shift+" increases it!
DVD Playback:
MediaCentral automatically found my video-ts folders and added them to the list in the "DVD" section, nice. The left/right arrow keys skip backward/forward through scenes however there is no way to fast forward or rewind! I also had an issue when playing a physical DVD there was no way to skip the previews and drop into the DVD menu, argh.
EyeTV
Like CenterStage you can view and playback your EyeTV content however the audio was just as badly out of sync.
It seemed to find my EyeTV device and attempt to access live TV through it ended up hanging just like CenterStage.
Movie Trailers
Like Front Row MediaCentral has a movie trailers section although they aren't quite as smooth and stutter-free in playback.
Music
You get access to your playlists as well as music by artist, album and genre which is pretty dang important. No album art tho' ;-(
WebTV
Unlike the other media-center apps MediaCentral lets you access webTV content by country which is pretty neat.
CenterStage

This project is only in pre-release 0.5 alpha but there is enough here to evaluate where they are going with it. It's worth noting upfront that CenterStage has perhaps the most potential of all the media-center apps out there right now as it takes a "server" and "client" approach where in theory you should be able to have one machine w/ all your media run the "server" (BackStage) and access it from any machine running the "client" (CenterStage).
Interface:
CenterStage wholeheartedly emulates apple's approach with a 3D rotating menu that allows you to select which media format you want to playback.
Looks just as good as Front Row and there is talk of making it customizable in the future. It takes a little while to startup (I assume it's busy launching BackStage) and then drops you into the Front-Row-Alike interface. The scroll wheel on my mouse wouldn't let me navigate in any of the screens, which is a bummer, so I was relegated to either mousing around or using the arrow keys on my wireless keyboard.
Looks like they are going towards an iTunes-type way of managing video media with options for browsing by Title, Actor, Director and Genre.
Seems like a nice way to organize your movie collection however I assume you will have to enter all this information manually as I can't divine how a centralized internet movie database would work given the multitudinous ways in which you can encode movie content. Still for the anal retentive among us it's a must-have feature ;-)
EyeTV
You can browse and playback EyeTV content within the interface or go to fullscreen mode, nice. Problem is that it's unwatchable. The audio is badly out of sync (by like 10 seconds or more) and you can see scan lines in the vide0 image.
As far as live playback/ control of EyeTV goes there is a placeholder for "Firewire DV device" which i assume will allow you to eventually playback the live video stream (perhaps from my firewire equipped set-top box too?!). However it doesn't seem to be enabled yet as I just get a black screen that requires me to quit the program as I can't back out of it using the escape key as one would expect.
The music playback function grabs your iTunes Playlists and displays the Track, Album and Artist info w/ corresponding album art (if any) which is nice. Would be nicer if they threw in an option to automatically find the album art for those you don't already have (yeah, yeah there are iTunes plug-ins but they don't work all that well when you are dealing w/ 30,000+ songs). As it is the 0.5 alpha seems to deal w/ small playlists fine but choked on my full library.

DVD playback doesn't work yet
iTheater
Well they got an alpha version out the door by january 31st so good for the itheaterproject.
Interface:
iTheater uses a scrolling interface (yeah still no scroll-wheel control) similar to MediaCentral) to choose which media-type to play. It's not so mac-tv friendly though as it is too small to read from across the room.

That's all you get for right now as there's no functionality included yet (no video or audio playback etc) so it's really just more of a teaser than an actual application.