If anyone is interested, last year on Team 2339 we used swerve drive. Our code is on github: https://github.com/Robolopes/RecycleRush/tree/master/2015RecycleRush.
The swerve drive math has been generalized to handle any number of wheel and to be able to rotate about any arbitrary point (like the center of an RC). Probably not useful this year, but just FYI.
Some notes on the math used are here: https://docs.google.com/presentation/d/1J_BajlhCQ236HaSxthEFL2PxywlneCuLNn276MWmdiY