Seems like the Bulldozer/AM3 report was a miscommunication or something. Here's a thread confirming (?) that Bulldozer will run on AM3+ only (not AM3): http://hardforum.com/showthread.php?t=1589613
It would be easy for a manufacturer to ship socket AM3+ and people to put AM3 chips in it without realizing they have a AM3 socket. Maybe the point of the quote is there are at least two boards in the retail supply that already have AM3+ sockets and just need a BIOS upgrade to support Bulldozer?
FWIW I'm using a X3 720 in a M2A-VM. When the M2A-VM first came out they called it socket AM2 but later updated the BIOS to support AM2+ and AM3 chips. Physically and BIOS wise the board I'm using will accept and run normally with a AM2, AM2+, or AM3 CPU.
Presumably the AM3+ boards will support AM3, AM3+, and something coming later. AMD is just taking turns adding and subtracting pins and they are doing it in a fashion that allows you to reuse parts for a while but eventually the reset has to come. Can't do that forever.