It is a single-core Ontario CPU and it comes without a GPU, so it will be able to work with a 5.5W TDP. This matches the magical TDPs of Intel's CULV Core 2 Solo SU3500 clocked at 1.4GHz which was the best TDP for Intel's non-Atom cores. Most CULVs that Intel sells today are 10W, but again Atom N200 series has 2.5W TPD which is drasticaly lower.
The latest generation Atom N4xx has a 5.5W TDP with graphics and memory controller included in the core, which means that AMD's Bobcat-based core won't be as power efficient as the latest Atoms.
Again this will be the most power efficient AMD to date, and its scheduled to come in 2011. This CPU targets the embedded, notebook and small form factor market.