Ok - I found the responsible reg key that breaks the ability to forward an MMS when you are actually viewing the picture. When you view a picture with either GC's and DCD's versions, and goto the Menu and hit Forward, it takes you back to the SMS \ MMS screen only.... This cab will fix that key....
az
See my thread on XDA for the cab.....
http://forum.xda-developers.com/show...05#post2394805
Update - GC14 will be updating the original MMS cab to include the fix. Those who wish to get the updated MMS cab can find it here
http://forum.xda-developers.com/showthread.php?t=404345