UDP works great. We did it last year between Python on an rPi and the roboRIO running Java. Take a look at
http://www.chiefdelphi.com/media/papers/3189, it points to our RoboRIO code.
We didn't get around to publishing the rPi end

but I think the students grabbed it from a tutorial.
The nice thing we did was use JSON for a data format. That worked very very well.
Let me know if we can help!