New to the game, maybe late to the Plex party, but HOLY CRAP, what a great app. Took a little tweaking to get everything working, and I hate the fact that it will not play my iTunes DRM stuff, easy enough to jump to Front Row from within Plex (assuming Apple doesn't delete it with Lion, they can stop support, but I see no reason to delete it) but otherwise it is a great media server.
Tons of channels to select from, Hulu and NetFlix support and more. My only complaint is that for some channels I am getting an odd error stating the media cannot be played. Haven't figured out why, since it is streamed content and not local. Also kida sucks you cannot jump from full screen to windowed and back from the remote. No matter, I ordered up an Apple Wireless keyboard so I can do what I need from my couch and leave the MBP tethered to the TV until I buy a mini as a dedicated media server, with the refresh coming, refurb mini's should be cheap and should be fine as a good server with a big NAS storage device attached to it.
But it is cool, and using my old itouch 2g as a remote is awesome, not to mention that is streams content on that device too, unlike Apple's Home Sharing that decided to forget about older devices.
I am a convert! And all this for $4.99 IOS app.