Mozilla outs Thunderbird 3.1 alpha
Among the tweaks are enhancements to stability and memory usage, better IMAP access, fixes for smart folders, filters, and attachment handling. The Thunderbird interface is also being re-tooled -- so far the changes are fairly subtle.
Thunderbird 3.1 is also dropping support for Windows ME and older as well as Mac OsX prior to 10.4 Tiger. But hey, if you're still running an OS that old you're probably not too concerned with running up-to-date apps either...
Ready to take it for a spin? Testers can download alpha builds for Windows, Mac, and Linux from the Thunderbird early release page.