They've agreed verbally, but no paper has been signed yet. http://www.mixedmartialarts.com/news/399078/Antonio-Nogueira-vs-Cheick-Kongo-scheduled-for-UFC-149/ That sounds like a good first step back for Big Nog since his arm was snapped like a thick pencil by Frank Mir in their rematch.
Kongo is probably going to knock him out. That just seems like a bad match up to me. Nog doesn't have very good take downs, unless he can get Kongo down, I think this is ending bad for Nog.