I use the Firefox extension Update Scanner to much the same effect: <a href="https://addons.mozilla.org/en-US/firefox/addon/3362" rel="nofollow">https://addons.mozilla.org/en-US/firefox/addon/3362</a>.  No complaints so far, although my use has been mild.  Note that you'll need to install via the beta channel if you've got Firefox 3.6.