How do I upgrade Firefox?
 

The Update Manager updated me to 3.6.

Thanks, but I don't like the idea of beta.

Update Manager will keep you at the latest version in the Ubuntu repositories. Ubuntu is not a bleeding-edge distro and AFAIK they generally don't use beta's.

3.6 is already the latest stable version for firefox
in particular, 3.6.13

so, unless you want to try out the firefox4 beta, you do not need to update firefox at all :P

In Synaptic, you can go to Settings-->Repositories-->Updates and enable pre-release and proposed updates. Not that I would, you know.

And I would consider Ubuntu, if not bleeding edge, at least edge, when compared to, say, Slackware and Debian.