I installed Firefox 3.0 beta 3 earlier this evening - it's decidedly faster than 2.0 There have been numerous changes. The address bar has updated & heavily modified as well to make it easy to revisit the website that you have visited before. It supposedly plugs the bad memory leaks that plagued it before. Time will tell on that one.
Here's a review from news.com.au - http://www.news.com.au/technology/story ... 18,00.html.
You can get the beta here - as the article says, unfortunately some of the Firefox extensions for version 2.0 may not be compatible with the new version. I've left my old 2.0 version installed as well as my ftp extension is not yet compatible with 3.0