After the difficulty I had with the WordPress 2.6 upgrade, I was both hopeful that 2.6.1 would fix some of the bugs, and a little hesitant about the upgrade. Apparently both my anticipations were incorrect. WordPress 2.6.1 was released yesterday, and while there’s no explicit mention of the admin cookie bug that I hit on the 2.6 upgrade, my own upgrade to 2.6.1 was pretty easy.
The full fixed bug list is on the WordPress Trac, so you may want to see if there’s any fixes you need. As another commenter pointed out, there are few security fixes, but that doesn’t mean there aren’t any–the thing about a plugin without headers not appearing on the plugins page raises concerns about hidden malware that might be worth upgrading to avoid. Just remember to clear your cookies before you try to log back into the admin console after the upgrade.