According to recent AMD documents that we were able to see, AMD is planning to launch a new Athlon series sometime in June of this year.
The AMD roadmap indicated that there will be several flavors of the Athlon II to choose from. When the new CPUs ship, there will be at least a 2, 3 and 4 core Athlon II all based on the same architecture. In fact, the new Athlon II's are very much based on AMD's current Phenom II. Although similar to Phenom II, the new Athlon II CPUs will not ship with shared L3 cache, which something that the Phenom II's do have.
AMD's roadmap also indicated that the upcoming Athlon II's will be based on socket AM3 and support HyperTransport 3.0 and DDR2 and DDR3 memory.
In terms of frequency, the minimum spec is 2.8 GHz going to the quad-core Athlon II, while the dual-core rings in at 3.0 GHz. The Athlon II's will also carry a maximum onboard cache of 2 MB.
Positioning for the new processors seem to indicate that the Phenom brand will take the high end while Athlon II will take much of the mainstream and lower end.