Since it seems unlikely we will ever get to see a completed BB, have the devs shared what they were planning to do? It'd be nice to know, just to satisfy my curiosity! It seems like they could at least tell us what the quests and instances were going to be like.
They did hold that contest to name the boss for the area. Supposed to be the 'Registered Offender'. But, BB has definitely been halted as well for the rest of the game and they even refunded the BB pass. I don't expect to see anything from the area.
I seem to remember reading somewhere that it was supposed to have links to games like word bump and slots, but it was also supposed to have new games too. I wish I could remember where I read it though. I'm sure that anything I read about it was before October '09 though.