http://www.meanpc.com/2011/12/ti-lau...duino-uno.html
Arduino has a much bigger community and is much easier to get started with. MSP430 is really cheap and low power. Can even be powered with fruit.
My robotics team (NCSU underwater robotics) used to use 3+ arduinos on our robot. 3 were for thruster control with H-bridges and additional ones were for peripheral devices. On the motor board, we had each arduino controlling 2 thrusters. We've been making the transition over to using MSP430's because they are much cheaper.