Anti-phishing capability, which Mozilla has branded "Safe Browsing," is one of the marquee features in Firefox 2.0 and one of the reasons a third alpha is necessary. Now baked into Firefox 2.0 alpha 3, Google Safe Browsing is triple-licensed under the Mozilla Public License (MPL) 1.1, the GPL 2.0 (define) and the LGLP (define).
Safe Browsing inspects a visited site against a regularly updated list of known phishing sites. The list of phishing sites may be downloaded automatically within the browser or can optionally be checked against Google's online list of known miscreants.