As of R2008b, Matlab uses a new symbolic engine (MuPAD instead of Maple). If you want to use mml with >R2008b you have to substitute the following line in mml.m:
I use Design Sciences MathType equation editor in MS Word with MATHPLAYER to create and display XML/MathML files that contain supplemental notes for my students in electrical and computer engineering. I also use MATLAB. I was pleasantly surprised and very pleased to learn of this submission. I hope that MATLAB will increase its support of MathML so that it matches or exceeds that of Mathematica and Maple.