The i7-6660U is a Skylake-U processor which has low power consumption. It appears to have replaced the Core i7-6650U which has been installed in Laptops since September. The new chip can manage 200 MHz operating frequency at the same price level as the older version.
According to Chipzilla the chip is made using 14nm and has two CPU cores, clocked at 2.4 GHz, and 4 MB of last level cache. It can run 4 threads simultaneously. It has the bog standard Iris 540 graphics and the 15 Watt TDP.
The i7-6660U supports all the usual Skylake extensions and technologies, including AVX 2, AES, Turbo Boost, and VT-x / VT-d virtualisation.It is hitting the shops with a $415 it is not clear when it will be under the bonnet of any notebook.