Hello there,
I have notice in the past few days that I cannot config the sidebar in my blog just by drag and drop (and therefore I can't change the order of the widgets or add new ones) when using WordPress.com through the latest versions of Firefox and Firefox Aurora. The button "get a shortlink" when editing a post doesn't work either.
Everything works fine using Chrome, and all those things work perfectly through Firefox in my self-hosted WordPress blog.
I'm using MacOs X 10.5.8.