when you get down to:
The AM2+/DDR2 Deneb 45nm processors have been specified to support only dual-plane motherboards. These processors will exceed current specifications when paired with a single-plane board. AMD is also recommends that ODMs do NOT support these two AM2+/DDR2 Deneb parts on any single-plane boards.
That is explained @:
Overclockers.com - Deneb Upgrading News
Since one of the few differences between the AM and AM2 mobo standards is a split power plane between the CPU and IMC for AM2s, this seems to say that these Denebs will be fine in AM2+ boards, but not AM2 boards.
A Deneb Quad-Core 6MB Shared L3 AM2+ @ 3 GHz coupled with openSUSE 11.1 and SLED11, looks very interesting to me;)