Final Fantasy Versus XIII was first unveiled at the E3 gaming expo in 2006. It's now 2011, and the game is not out.
To be fair, Square Enix said in 2006 that it had not yet begun work on the game. But by late 2009, Square Enix was showing gameplay footage of the title. Square Enix would not confirm a 2010 release, and the title obviously wasn't released.
Back in 2009, Square Enix's Yoshinori Kitase told Kotaku that the development for Final Fantasy Versus XIII was "comparaitvely faster" than Final Fantasy XIII.
A trailer was shown at the 2010 Tokyo Game Show, but the title was M.I.A. at this year's E3 gaming expo. In the latest issue of Japanese game mag Dengeki Playstation, Square Enix Tetsuya Nomura apparently said that the game won't be at this year's Tokyo Game Show. (Though, I'd imagine at the very least there will be a new trailer.)
Though, Nomura did say, "We're deciding when to make more information about Versus available to the public."
Earlier this year, Square Enix did show a new trailer for the game, giving hope that the title is still in production. The Tokyo-based game maker also shot down talk that the game was going multi-platform as former PS3 exclusive Final Fantasy XIII did when it was released on the Xbox 360.
But for now, Final Fantasy Versus XIII exists in trailer form only. And you can't play trailers.