This is probably basic/simple stuff, but here's a quick (raw) video of a fully autonomous wheeled take off in a Senior Telemaster. The basic strategy used so far is to steer with the rudder to hold heading error to zero. Then when airborne, use a small amount of gentle bank to steer the heading error to zero. My roll gains could be better, but they finished the day much improved over the start (and hopefully will continue to improve as I have a chance to review the flight data.) There is some lateral drift as you can see, but probably on par with the performance of an "average" RC pilot, and on this day there was some moderate cross wind component to deal with.
The autopilot system we are developing uses the APM2 for sensors and then a gumstix overo for all the heavy lifting and computation. I have a series of blog postings starting here that show a bit more about the system.