Mark Pilgrim just recently patched a long-standing bug in Firefox (the fix will appear in Firefox 3). Currently, there is no way a user can disable timed redirects through META refresh elements. This becomes a gigantic problem to blind users who utilize screen-reader software. By the time the screen reader starts reporting what's on screen, the page changes unexpectedly.
What I find most intriguing about this new system is that the notification bar appears just like an ALERT to assistive software. Mark has a blog post that goes into way more detail on the fix, so check it out if you're interested. It's really good to see Firefox making strides in this area. Yet one more reason that Firefox 3 will be super awesome.