I finally got the MCG-2 large grip for the E-P3.  First impression was, well that isn't very large.  Then I took out of the plastic bag and was immediately surprised with how grippy the rubber surface is.  I put on the camera, and it does help a lot with grip.  The rubber/plastic material is like what you find on the non-slip Hogue grips for tools.  The grip isn't as deep as the GH2, but you can get a good grip with two fingers now unlike the old just for looks grip that was included.