They will work soon, they always do. You can still run 3.5.7, too. Firefox is a fast developer and for the most part, know what they're doing. The plans are for 4.0 to be released by the year's end, but it's not carved in stone. IE9, anyone...............
Firefox 3.6 is an excellent browser, one that you can customize the way you want. There are thousands of add ons to choose from, but at the time, there's still a few from 3.5.7 that you can't get. But shortly, they will be there.
Welcome to the forums, dustinoe08! I didn't notice any difference in my tabs or toolbar. Try uninstalling and reinstalling latest Firefox, see if it helps.