i upgraded my test forum and the most annoying issue is that the avatars are no longer resized in the topic view. instead they show up in full size which destroys the whole topic list view. :|
I am using the blue-grey theme and safari 5.1.1 on a mac. the same issue is with the red-grey theme.
for at least the yaf pro theme there are no issues. with the avatars. therefore I guess that there might be a glitch in the *-grey themes.