How should I go about getting Firefox 3.5.2 installed on Jaunty, are there any semi-official places I can pull a deb from?
Go to the Ubuntu documentation FirefoxNewVersion page.
When a new version of Firefox comes out, there is some delay until it can be downloaded and run. This page will explain how to install Firefox as soon as possible.
Follow the Instructions for the impatient that give
Jaunty and Karmic installation instructions for firefox 3.5.
Low difficulty, high safety: these packages are maintained and fully tested by the Ubuntu Project