For reviews, AMD has indicated only three boards that feature full compatibility with Phenom II. The Gigabyte MA790GP DS4H, MSI DKA790GX Platinum, and Asus M3A78-T have all been given the thumbs up by AMD for full support with Phenom II. I personally was shipped a MA790GP DS4H from Gigabyte which booted with the Phenom II X4 940 albeit as an “unknown AMD x86 Processor”. A quick flash to the F3M BIOS and I was booting Windows Vista without any issues.
It is sort of unknown right now which boards in the future will support Phenom II, but in theory all AM2 and AM2+ boards should work so long as the manufacturers update the BIOS accordingly. Keep in mind though that there may be limited overclocking support especially on less popular boards and older SB600 boards. If you are looking for an AM2+ board that will let you fully utilize your chip, one of the boards above would be a good choice or personally contact your manufacturer of choice to see what their official support will consist of.
Earlier, I mentioned socket AM3 and future CPUs. Socket AM3 processors will feature a hybrid memory controller that will work with DDR2 in AM2 and AM2+ boards and a DDR3 memory controller that will work in AM3 boards. The initial Phenom II X4 920 and 940 though will only support socket AM2+ and DDR2, so keep this in mind. Rumor has it that AM3 processors will launch in February, so if you are looking for the most flexible processor it may be worth your time to wait.