disappearing icons
The eject button on my dock, for instance will sometimes disappear.
Many applications just have a generic application icon. Many files have no icon whatsoever (i can only identify them by the filename underneath).
In general, it seems like 10.6 is trying to redraw icons more (when opening a stack for instance), and that the process seems noticeably slower.
The odd thing is that opening in coverflow will force the icons to redraw, but then the images in coverflow are sometimes different from the actual icon.
MacBook Pro, Mac OS X (10.6)