According to Deadline.com, Paul Lieberstein signed a 3-year deal with NBC Universal Studios, which includes continuing to serve as showrunner/executive producer for The Office.
The article includes some interesting tidbits about the origin of his role as hapless HR rep Toby Flenderson, as well as The Office Season 7 finale.
P.S. The Office Season 8 has been confirmed, no other seasons beyond that. (Yet.)