One of the new features in Firefox 3 to make phishing harder is URL highlighting:
The Firefox 3 Alpha 7 build incorporates the Locationbar2 add-on and displays the domain and subdomain information of any given web address while fading other address information to a lighter shade of gray, as shown below. (You can also find the relevant Bugzilla entry on this new feature available here). In theory, this change should make it easier for end-users to recognize when they've been handed a malicious domain address masquerading as an actual official web site. In keeping with this change, FF3 Alpha 7 also incorporates a domain translator that changes an address that's encoded in non-standard ASCII (such as a percentile-encoded address) into standard text. Again, this is a change aimed at making domain addresses easier to read by stripping out the non-standard characters a phisher might use to confuse a potential target.