I have just found and tested a Blockset that interfaces MATLAB/SIMULINK and Arduino. You may find this at:
I highly suggest this program since it offers rapid prototyping capabilities to the famous and cheap arduino. The guys have build a block that interfaces with the Real Time Workshop of MATLAB and have also implemented C functions for all arduino operations (analog in, out, serial read/write etc.). Despite the fact that the code is obviously bigger one can gain advantage from the quick and abstract way of programming that simulink offers. It is a good work!