How to enable USB tethering on your Android phone to Mac OS X Lion
There is a native RNDIS driver for Mac OS X that allows you to use your Android phone's native USB tethering mode to get Internet access, it is called HoRNDIS:
http://joshuawise.com/horndis

It is known to work with Mac OS X versions 10.6.8 (Snow Leopard) through 10.8.2 (Mountain Lion).

HoRNDIS is also available in source form on GitHub,  it is licensed under the GNU General Purpose License, version 3:
http://github.com/jwise/HoRNDIS