Tensilica are shipping the Extensa 7 at 250MHz & 0.082mW (yes, that’s MILLIwatts, overclockers) per clock cycle.
To polish the Penguinista perspective, they are available with MontaVista Linux. They’re billed as “post-RISC” style processors, so they can do sneaky/fast VLIW instructions, & “even extend the architecture with C/C++ application-specific instructions” for those of us who absolutely have to eke out the last skerrik of performance from every device which falls into our hands.
According to Tensilica, the Extensa 7 churns through twice as much code as an ARM7TDMI-S while drawing roughly half of the power.
The LX2 variant of Extensa also does faster I/O, is better optimised for VLIW-style instructions, & stars a high-speed 7-stage instruction pipeline. All chips include various error-correcting & power-saving sneakiness.