FOOTAGEHEAD Tiger users/ iMac (10.4.11) beware !! Upgraded from 1.1.2 to 1.1.3 and had iChat problems.
At first did not realize it was Perian, but noticed that although my iChat still connected for video chats, all I could see was me (not pleasant) and not the person I called. They could see
me and no problem with audio either. Found the answer in the Apple Support forum discussion moderated by Ralph Johns, an iChat wizard http://discussions.apple.com/profile.jspa?userID=208. Kudos to him.
Downgraded back to 1.1.2 and all back to normal.
(Version 1.1.3)