Even though Firefox 3.5 has just been shipped this year, they are planning to go forward with the release of Firefox 3.6 Alpha 1. With codename as Namoroka, it has quite big changes with Gecko 1.9.2 as the engine. The wiki entry marks November as the scheduled release month for Firefox 3.6, which will be considered a minor updates opposed to major updates like what Firefox 3.5 did to Firefox 3.0.
The cool thing is that Firefox will have faster and better performance compared to previous version, new graphical tab-switching behavior, and many web standards addition (mainly CSS 3).
Please read some quick review here