In May, we reported that Alan Tudyk (Firefly) had joined the cast of Michael Bay's Transformers 3, but we didn't know what his role was.  In the article, Steve said he hoped that they would use Tudyk in a fun role and not something dark and serious (Tudyk's talented enough to do either or both, although I know Steve didn't mean to imply that he wasn't).  Well, we now know it's going to be a fun role as Tudyk has told Mira Sheila Sharma at From Hollywood With Love (via tfw2005 via /Film) that he is playing a Sector Seven Agent:

"I’m a fellow agent of [Agent Simmons (played once again by John Turturro)], that is sort of his assistant and weapons expert, computer hacker, cyber sleuth."

Transformers 3 is slated to open on July 1, 2011.