It can be downloaded at the normal location – www.getfirefox.com. On the surface it looks visually pretty much the same, but has some nice features, and a couple of core add-ons that are not compatible with 3.5. For the new stuff:
- Private browsing mode
- Faster JavaScript execution
- Can drag tabs into new windows
- “Forget this site” as a finer tuned scalpel for removing remnants of specific sites.
- Improved offline browsing
- New features that we need to wait for web sites to catch up on:
- Location Aware Browsing
- Downloadable fonts
- Embedded open video format support
- HTML5
- Native support of JSON
- and more check out https://developer.mozilla.org/En/Firefox_3.5_for_developers for more details
So the good news is that WordPress 2.8 works without a hitch (at least so far 
). Google Gears however is currently disabled as it is not compatible. The interesting part is that HTML 5 supports local storage and so is somewhat competitive to Gears, so it will be interesting to see what Google does to Gears when it runs inside a HTML5 browser. I’m hoping I dont have to wait for Gears for too long
For me I’ve not encountered any problems. So to sum up – I dont see anything particularly broken about this release. Which is always nice and reassuring when a release comes out and you dont need to back it out 1 hour after installing it!
Gareth