Davide Bresolin has an OS/2 build of Enigmail 0.89, including updates for Thunderbird 0.9 and Mozilla 1.7.3 to use it; this allows you to use GnuPG with your email. Hopefully, the patches necessary will make it into the next official releases of Thunderbird and Enigmail. He has also made available a build of Mozilla Calendar for Thunderbird 0.9.
http://www.dimi.uniud.it/bresolin/warpzilla/
Source: OS/2 News and Rumors