Well, I have a fully working solution for BlueZ (under Linux), which is very simple. I made a firmware that can receive simple commands over the air (most of them concerned with controlling the motors), and it continuously sends back sensor readings (supporting RGB readings for the colour sensor and single shot mode for the ultrasonic sensor). The PC side is a tiny C program that most likely can be easily adapted to other bluetooth libraries, e.g. Bluecove if you use Windows.
If you or anyone else is interested in this particular solution, just send a PM. If it matures a bit, I could throw together a public version too.