Updated http://www.mozilla.org/ports/os2/ today. Mike didn't tell anyone about the new releases until yesterday.
January 4, 2007 Thunderbird 2.0 beta 1 has been released.
"Features new to Thunderbird 2 include message tags, folder views, session navigation history, a visual refresh of the theme, and improved new mail notification alerts."
Release Announcement:
http://www.mozillazine.org/talkback.html?article=20220
Requires a libc0.6.1 based version of the GCC runtime library.
ftp://ftp.netlabs.org/pub/gcc/libc-0.6.1-csd1.zip
Source: OS2VOICE