Unfortunately, we don't have a timetable for this at the moment. We should know more before too long. If AOL will Open Source PLS, as they've done with AOLserver, then we're in Fat City because PLS apparently works very well (Ben Adida has personal experience with it and has enjoyed that experience).
If not, there are other strategies we can take which involve more work. "Summer" is probably the timeframe, I'm afraid. We could lash together a slow and laborious site-wide search in the near term if necessary, which would suffice for new sites with little content.