One thing which has been preventing me from upgrading to Firefox 3.6 is the lack of support for IE Tab which, as you may know, allows you to run a site using the IE rendering engine inside of a Firefox tab. I need this for some sites such as Sharepoint and the Virtual Server control panel (so I don't have to open IE directly).If you are facing the same situation, the workaround is simple: uninstall IE Tab (which appears to be abandoned) and go with Coral IE Tab. Not only does Coral IE Tab pick up where IE Tab left off, it adds a couple of really useful features:

• Support Adblock Plus. Ads in IE page will also be filtered by Adblock Plus!
• Support sync cookies between IE and Firefox. Now you can switch between Firefox tab and IE tab without having to relogin!

I have been using it for a few days now and it seems to be working great. Once Firefox releases their first patch for 3.6 I will be upgrading without the worry of losing functionality.