Mathematica 9 was just released Nov 28 which caused me, of course, to have a look to see what wolfram has done in way of comparing itself to maple. 

Perhaps we can discuss, compare, debunk, clarify some of their claims or perhaps dismiss the results altogether

Here is one speed comparison chart I came across.  Is it relavent?  It shows Maple 16 as the worst performer.

One thing that impressed me (eye candy always does) was the new 3d volumetric processing http://www.wolfram.com/mathematica/new-in-9/3d-volumetric-image-processing/

Volume rendering recalls me to a post/question I did a long time ago http://www.mapleprimes.com/questions/35766-3D-Matrix-In-Maple  I don't know if mathematica picked up on that and started implementing a volume rendering engine, but regardless they now have such a beast.  Almost a math discovers photoshop concept. 

Another one that perked my eyes was the new signal processing and analysis.

The expanded visualization and controls looks just like a copy but enhanced Maple version of dials and guages concept. 

I think most of mathematica's strength in their new release is the developement of it's image processing abilities.