CPU World reports that Intel is working on three new ULV (ultra low voltage) Sandy Bridge processors due later this year.



From MacRumors:

The three new processors increase the clock speed over their existing Sandy Bridge ULV processors from 1.4-1.6GHz to 1.7-1.8GHz while keeping the TDP (thermal design power) at 17 Watts. The TDP is one of the key factors in Apple's ability to fit these processors into their ultra-portable MacBook Air. At 17 Watts, these processors could indeed be used in Apple's MacBook Air.

  Intel Preps 1.7GHz and 1.8GHz Processors Suitable for Next MacBook Air