I have a custom theme for one of my sites. When I tried it with WordPress 3.1, I noticed that the admin bar seems to think that all of my pages are category pages.
If I am on any page outside of the admin, the admin bar says "Edit Category", etc. as it would on category pages.
The admin bar is working as expected with Twentyten, so I am pretty sure this is an issue involving my theme. Let me know if you have any ideas as to why the admin bar is not working here.