Mozilla has released the second release candidate of Thunderbird 3.1, the last RC, cause the final will certainly be released next week. No new features were pushed into Thunderbird 3.1 RC 2, of course, but five bugs were crushed, one critical that affected the Mac build.
Users of Thunderbird 3.1 desktop email client can check for updates at Help -> Check for Updates. It is also available for download for Windows, Linux and Mac operating systems at Mozilla Messaging.
Major features in Thunderbird 3.1 include; faster search results, Quick Filter Toolbar, a new Migration Assistant, a new saved Files Manager and a Mail Account Setup Wizard. For details on these new features read here