Firefox 1.5 has officially been released!
I have it installed and am checking it out now. I think the best feature overall is “drag and drop” capability for browser tabs.
One thing to note:
If you have a lot of Firefox extensions installed, you may want to see if there are 1.5-compatible versions available before completing the upgrade. I had many extensions that had no equivalent and were consequently diabled 🙁
Ay any rate, enjoy!