Firefox 3.6 is Here!

If you are upgrading there will be issues with some extensions (as usual).
To upgrade, click on Help, check for updates and follow instructions

If you are using Tab Mix Plus, after you upgrade to 3.6, manually install the new version of Tab Mix Plus from here.
After installing the Tab Mix Plus update, restart Firefox, go to Tools, Add Ons and Enable Tab Mix Plus and restart Firefox again.

If, when Firefox 3.6 starts up, you get a log of errors and warnings, it could be that you have some incompatible add-ons causing problems. Go to Tools, Add-ons, and Disable all the add-ons with red exclamation marks and restart Firefox. The problem should be fixed.

Make sure you have Mr. Tech Toolkit installed so you can make your fave add-ons compatible.

You might want to disable any add-ons you had to deal with memory as 3.6 seems to handle memory issues better.

One thing new to 3.6 is Personas. Install the Personas Plus add-on here. See the green button in the lower right to install the add-on.

Here is an article at PC World on some of the new features