When the rumor first hit, it was almost immediately debunked by Maguire himself. But with his departure from Spider-Man 4, the rumors are back, with several sources claiming that he will indeed be shrinking down as Bilbo Baggins.
The main source is the British rag The Sun(I know, I know..)According to them, a source told them the following..
"Everyone is over the moon. Tobey is not only one of the most recognizable faces in Hollywood, he is also one of the best actors."
Supporting that, is AMC Entertainment blogger John Campea, who recently tweeted that someone close to production has leaked the same news to him. He said..
"I have been personally told by a source very close to Guillermo del Toro that it's true... Tobey Maguire IS
The Hobbit."
So you see, it has to be true!! But seriously, it might just be worth keeping an eye on. If it is true, expect an official announcement pretty quickly, if not(most likley) expect more debunking. Further developments as we get em.
Update: Just as we thought, debunking it is! Harry over at AICN emailed Peter Jackson and Guillermo Del Toro directly and received this response..
From Jackson..
"No truth at all, although we're all big fans of Toby. We are currently auditioning for Bilbo, and a month or two away from any announcements.
Cheers
Peter J"
And from Del Toro
"Its not true, gordito-
G"