Just after Firefox 2.0 release, Mozilla team seems to be getting busy in working on next version. The PRD is already there which is said to be based on the 1.9 release of the Mozilla platform, Geeko. The PRD for Firefox 2.0 and 3.0 are merged into one and hence PRD for Firefox 2.0 redirects to Firefox 3.0. The document is in form of a wiki.
Requirement includes Less than a 5.0 MB download on Windows, Floating icons/toolbars, revive Inspector Options panel.