Well, it's official. Firefox 3 is available in beta. The improvements described in the release notes fall into the main categories of security, usability, development platform, and performance. The items that directly have to do with SSL include:
Click the site favicon in the location bar to see who owns the site. Identity verification is prominently displayed and easier to understand. In later versions, Extended Validation SSL certificate information will be displayed.
New SSL error pages: clearer and stricter error pages are used when Firefox encounters an invalid SSL certificate.
Bob Lord gave us detail on those bad SSL Certificate responses recently. We also see a reference to advances in Firefox's equivalent of Phishing Filter:
New Web Forgery Protection page: the content of pages suspected as web forgeries is no longer shown.