KevinKubasik and Pierre have been working diligently on a backend that can index the wealth of data that can become locked away is Mozilla's obscure mork files. (Huge props to Pierre for pretty much all the mork processing work)

Active development can be seen in Kevin's personal SVN repo at

https://kubasik.net/svn/beagle

However, because of the frugal nature of servers at home (and Comcast generally stinking at life), I have attached a tarball to this page containing the most recent (as of Friday June 23rd 12:14am EST) snapshot of the thunderbird backend (in the full beagle tree).