If you're one of the lucky ones that is. It's PC only right now, but I'm gonna go ahead and guess they're gonna try and get the PS3 in there too at some point. If you didn't get in right now and wanted to, they'll probably open it up later on.
Source
September 22 for the collector's edition; September 30 for the regular. The collector's edition gets you an exclusive item, a making of DVD, and an art book. Not a bad deal (especially the week of extra access). Both editions get a month free too.
Source: http://kotaku.com/5576618/final-fant...-release-dates
Sad that you couldn't go to E3? Here's something to make up for it: http://na.square-enix.com/e310/index.html
All the trailers for the games Square-Enix is showing at E3, plus a channel to ask questions directly to the developers.
Here's a list of games being featured by Square Enix this year at E3.
Final Fantasy XIV (PS3, PC)
Deus Ex: Human Revolution(PS3, Xbox 360, PC)
Kingdom Hearts Birth By Sleep (PSP)
Kingdom Hearts Re:coded (Nintendo DS)
The 3rd Birthday (PSP)
Front Mission Evolved (PS3, Xbox 360, PC)
Kane & Lynch 2: Dog Days(PS3, Xbox 360, PC)
MINDJACK (PS3, Xbox 360)
Dungeon Siege 3 (PS3, Xbox 360, PC)
Final Fantasy: The Four Heroes of Light (Nintendo DS)
Lara Croft and the Guardian of Light (PS3, Xbox 360)
Necromachina (Xbox 360 [Xbox Live Arcade])
Space Invaders Infinity Gene (PS3 [Playstation Network], Xbox 360 [Xbox Live Arcade])
Final Fantasy Tactics: The War of the Lions (iPhone, iPod Touch)
All of these games can be found at the E3 Virtual Booth, located here: http://na.square-enix.com/e310/index.html
No idea on which of these is "Project X". I can't find it anywhere.

Playstation 3 and Playstation Portable Owners, ready your credit cards!
On June 15th, PS3 and PSP owners will be able to purchase and download Final Fantasy IX straight to their systems from the Playstation Store.
The game will follow Final Fantasy VII and Final Fantasy VIII, and cost $9.99 to download.
Source: The Playstation Blog
In other news, the Electronic Entertainment Expo starts on the same day (June 15th) and runs through until the 17th. While we cannot physically be there, we'll be reporting all we can on Square Enix and related companies who are attending. So make sure you subscribe to this Blog if you want instant notifications of new posts.