Nope, I just checked and you can't edit the subject, although you can change the subject in the replies, but it only applies to non general/tradeskill/server/etc forums.
Edit 2: It DOES change the subject in the "Last Active Thread" column on the forum listing page though, which IMO is a glitch.
Edited, Thu Jan 27 00:56:08 2005 by MMORPGFan
Edited, Thu Jan 27 00:59:42 2005 by MMORPGFan