Mozilla just released the latest beta of their Firefox beta.  You can get it here.  Unless you’re a particularly cunning linguist you’ll want English-US. 

To help those along that will inevitably claim it’s not that different from whatever version they were using before.  This is a great read.  It explains some of the changes in a relatively easy to understand way.  Also I learned about this.  You can select discontinuous text. Which I guess has been around for a while but I never tried it.  It’s pretty sweet.

Although it’s pretty stable, probably more than some companies release software.  It’s still beta and comes with all the baggage that entails.  Firefox 2.0.0.12 was just released recently and is good if you’re not feeling adventurous.  2.0.0.12 is the latest official version.  Your profiles once run with version 3 can’t be downgraded.  It’s recommended to create a new profile for Firefox 3 so you can go back to 2 if desired, at least until Firefox 3 is released later this year.  Another common complaint is add on compatibility.  The themes unless they’ve been updated for Firefox 3 are probably broken and the author will need to update them.  The extensions are less likely a problem.  A good amount of the most common extensions are already compatible, most will probably make release.  If you have a favourite extension that’s not compatible, there’s a few things you can do.  You can go to the authors website, a lot of them have special versions for Firefox 3.  You can get an extension called MRTech Local Install which does a multitude of great things, including forcing extensions to ignore compatibility.  Which is potentially a bad idea, but I’ve rarely had bad luck with it.  Another thing you can do is actually edit the extensions install.rdf file repack it and install.  That’s really geeky and is similar to forcing it to ignore compatibility checking, I’ve done it to  a handful.  Most extensions work fine, they just need one line edited in install.rdf and they’re good to go.  You can wait for the author to update it.  You can actually force themes to work too, but in my experience that usually turns out really badly.  If you do mess something up you can drop into firefox’s safe mode, or restore your profile from the backup that you most certainly made.

Warnings aside, it’s pretty painless for most people.

Also, if you’re curious what everyone else is running.  Check this out.