Just a few of the new or updated features included are:
Built in phishing protection will provide a warning if a suspected web forgery is detected. Phishing Protection is turned on by default.
Searching has been improved as has tabbed browsing (can tabbed browsing get any better?)
Another long-awaited addition is a built-in spell checker.See the Release Notes on Firefox2, Beta 2 for all the added, updated features.
Download and Installation Instructions