Dave Meltzer has confirmed on WrestlingObserver.com that Ryo Chonan has officially signed with the UFC:
UFC has officially signed Ryo Chonan, a former Pride fighter
Ryo Chonan I guess is going to be another Jeremy Horn in the sense where they import a challenger who holds a previous win over one of their champions who has cleaned out his own division.
When there weren’t a lot of options for Chuck Liddell to fight, they signed Horn just to headline a PPV so that they could sell the past history between the two. If Anderson Silva gets past Rich Franklin again at UFC 77 then I get the feeling that Chonan could be pushed in a similar role.