According to Lisa de Moraes of The Washington Post, Ricky Gervais and Stephen Merchant have officially stated that there will not be a third season of Extras (the story is at the bottom of this page). Just like with their other creation, The Office, the comedic creative team felt that two seasons were more than enough, and just like with The Office, the show will be wrapped up with a standalone special, air date TBD. Slightly more information is here, via The Hollywood Reporter.

In interviews, Gervais had been going back and forth on doing a third season, but I think most people knew what he and Merchant were really thinking all along. The two of them like the British format of short seasons that air whenever the creators get around to writing a new series, and they both seem like they like spending their careers doing different projects (Gervais is currently touring England with a one-man show called Fame). So hearing that Extras isn't getting a third season isn't a big surprise.