the mouse capplet does not work for themes with XFree86-4.3 because it has new cool cursor support. I don't know when 8.1 will ship but if it ships before gnome 2.2.1 someone has to hack something up.
*** Bug 81581 has been marked as a duplicate of this bug. ***
Fixed in rawhide.
*** Bug 83550 has been marked as a duplicate of this bug. ***