Information about two Z-series Atom processors was leaked today. One is 1.2GHz processor (Z515), which is extremely power-frugal and consumes just 1.4W when running at full power and as-little-as 0.65W when scaled back to 800MHz clock speed. However, with all these fancy low number, you will have to bear with slower 400MHz system bus and a 100MHz slower graphics core.
The second Atom is the first one to achive 2GHz clock speed (Z550). Interestingly, it still consumes 2.4W of power which is same as consumed by the 1.86GHz version.
The Z515 will be targeted at the low-powered MIDs and low-cost netbooks. Onviously, the Z550 will be targeted towards hi-end netbooks.