The new version of Mobile Email that was just released (aka "Mobile Email - Latest Version") caused my LG ENV3 to lose the ability to send picture messages. I believe it has something to do with the app's use of "push" email. It seemed to cause my phone to be constantly sending/receiving data, as evidenced by the little data arrow indicators.
The Verizon tech support rep veriifed that since downloading the app on 12/14, my data useage was off the charts. Good thing I have the unlimited data plan... 
Once the tech support guy had me remove the app, I was able to send pic msgs again. So I guess it's back to the older Mobile Email version for me - until they fix this bug.
I'm curious if other users have experienced this same problem.
JohnB