Intel is apparently set to broaden it's Atom line-up yet further. According to HKEPC, two new Atom Z5xx-series chips are prepped for release, adding a new top and bottom rung to the Atom ladder.
The Z550 brings with it a 2.0GHz clock speed, while still needing no more than 2.4W of power and claiming an average consumption of 0.22W. Possibly a candidate for the like of Sony's Vaio P-series which is just a tad underpowered for Vista with its entry level 1.33GHz Atom.
Probably of more interest is the Z515 with a dynamic clock speed ranging between 800Mhz and 1.2GHz with a peak power consumption of 0.65W and 1.4W at each respectively. Average power consumption would purportedly sit at around 0.16W which is pretty impressive.
Both chips are said to launch this month, so we'll probably see them appearing in systems in the next couple of months.
HKEPC (Google translated).