I don't even see a publish.me.com entry in my Key Chain access anywhere. I'm not quite having the same problem, but I was hoping this thread would help. I have iPhoto 08 and when I publish to the MobileMe gallery, it starts but then gets hung along the way.
Summary of work around: After changing your MobileMe password at the MM website you need to provide your new password to MobileMe using System Preferences (this is normal). The work around is to also change the password for publish.me.com in Keychain Access. After doing this, the galleries in iPhoto will correctly sync with your MobileMe galleries.