A PPA on Launchpad is the best place to look for this sort of thing. A quick search finds https://edge.launchpad.net/~ubuntu-mozilla-daily/+archive/ppa, containing a thunderbird-3.0 package which you should be able to install alongside TB 2.
Note this is a daily build PPA, and will probably be somewhat untested, so YMMV etc. -- Josh Holland <j...@joshh.co.uk> (key F6067C12) http://joshh.co.uk dutchie on irc.freenode.net http://twitter.com/jshholland http://identi.ca/jshholland -- ubuntu-uk@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk https://wiki.ubuntu.com/UKTeam/
