Progress is slow but steady (I'm finding the balance between my many hats). Got sidetracked making a pretty skin for it (really gotta stop that, I'm supposed to be farming out the design work), but it's looking very good aside from the performance issues. I'm thinking Apache::PerlRun for now.
Of course, it's still read-only. I'm tempted to really push the SQL phrasebooking and drop in a phrasebook that will handle mwForum tables. That is, don't convert the mwForum data, just read and write it natively. I'm not sure how well that would work, given that mwForum has only categories and groups, not topics (well, it has "topics" but those are what Wirebird calls "threads"), and otherwise manages things somewhat differently.
I should probably not spend the time on it, though. Or if I did, I should spend it phrasebooking phpBB databases or something.

