I agree with many of the answers given above. Since the answer is specific to the diffset of MATLAB and R capabilities, I will mention a very important one: MATLAB includes a JVM and has flawless and robust interoperability with Java. All of Java's vast universe of libraries is accessible to the MATLAB user. The MATLAB IDE can be almost be used as a poor man's Eclipse. In comparison, rJava is very immature, despite the very valuable effort of its creator (Roman Francois).
