Dont believe (AMD) has said it going to be dual channel. Its a assumption people are making because AMD said AM3 processor will run on AM3+ boards.
If AM3+/ Bulldozer is quad channel, there is no reason a AM3 processor cant run in dual channel on a quad channel AM3+ board.
It could be one of the reasons AMD didnt want the Bulldozer on AM3 boards. They decided not to include a dual channel controller for space and one of the performance hits they clamied it would take.
Everything that i have seen thus far has pointed towards bulldozer being dual channel.
From how I understand it from articles out so far, initially all domestic desktop bulldozer chips will be dual channel, and some server ones will be quad.
Can see it in the future becoming triple/quad channel for the hgher end market if they have the controller for it, but how many people could afford to get a straight out quad channel memory set, idk. As it is DDR3 suppose if you already have 4 sticks running in dual dual channel on your current system and they would work together, could just drop them in quad channel if there were support out eventually