Asus just announced that it is possible via a BIOS update on some of their current AM3 motherboards to use an AM3+ CPU aka Bulldozer.
Asus just announced today that with a simple BIOS update you will be able to use upcoming AM3+ Bulldozer on their current 8-series chipset based motherboards.
Currently know AM3 motherboards that can be BIOS updated:
Crosshair IV Extreme
Crosshair IV Formula
You should be aware that chipsets for soccke AM3 and AM3+ are physically different, which is why cross platform compatibility hasen't been announced yet.
We will let you know when we will have more info.