I've update Tao.Cg to the latest version of the Cg Toolkit (3.0 - July 2010), and changed the API to be more OpenTK-like.
The core and GL APIs are fully wrapped. The GL part makes use of OpenTK data types. I've also ported 10 basic examples*.
Currently missing are some convenience overloads and xml doc comments.
*Some of the examples require glut.