Migrating the bboard data has been largely solved by your folks and Tilmann (though I never followed up to test his work, I just more or less trust him, and think that's a pretty good idea all-around).
SDM is the big deal after that, i.e. our running a parallel instance until a group of folk get together to recreate a 4x SDM. Woe is us, we're all damned busy with contract work and as been said more or less, the shoemaker's son goes shoeless.
SDM, integrated with the download package and a better than ACS 4 ticket tracker (I still like new-ticket) and then we have all the code we need for a pure-OpenACS 4 openacs.org.
