Along with a lot of other people I'm having dashboard problems after upgrading to 2.8. After some fiddling with the plug-ins, I've found that WordPress.com Stats seems to be blanking out the right hand column and disabling the pop-up menus.
Entering the URL for the stats page (...index.php?page=stats) shows that in itself it's still working. Disable the plug-in and everything else appears fine.
I was just curious to see if anyone else is getting the same problem for the same reason.