AMD may be quiet right now on the "grown up" ultraportable chipset front, but expect all that to change as the company rolls out its Shrike platform. Intended for full-power ultraportables, such as Lenovo's X61, rather than budget notebooks (which would be served by the Puma chipset), Shrike is built on AMD's Fusion chip; that includes both a CPU and separate GPU on the same silicon.
The benefits are the performance increase of having a dedicated graphics processor, the compact size of the chip itself (AMD state it's aimed at ultrathin notebooks less than 1-inch thick) and longer battery life. TDP is 8W including the Northbridge (versus in excess of 20W for Atom, including the Northbridge).
Don't look for it to be in machines any time soon, though. Preliminary suggestions are that Shrike will make it to market in the second half of 2009.