Finally you can download Firefox 1.5. It is available for Windows, Linux and MacOS X, offers plenty of new features and is even faster than before. Here are the full release notes.
If you're currently not using Firefox, check out the new Firefox with Google Toolbar. This is an offer from Google, they have enhanced Firefox with their useful toolbar. So Firefox gets even better, a highly recommended download!
As a bundle it is currently only available for Windows. If you have Linux just download Firefox 1.5 and then go to the Google Toolbar site with your Firefox browser. It works just fine with Ubuntu.