Comment 6 for bug 393978

hackel is right, Fx 3.5 will be deafult in Karmic.
Denis, update is already done, it is only being tested and as asac on #ubuntu-mozillateam told me, it should be released today for Jaunty.
More info here: http://www.asoftsite.org/s9y/archives/160-FAQ-Where-can-I-get-firefox-3.5-for-Ubuntu.html
If you install Fx 3.5 from Moz. Security repo, beware - it is still Shiretoko with that ugly icon and there is no localization.
Also, Fx 3.0 can't be uninstalled, because firefox metapackage depends on firefox-3.0, on which Java plugin and Ubufox depends (but If you don't need them, uninstall them as well).