[reprod]

I was able to get the Picture Mail working as per the OPs (technically)out of the box. It just took a whole day until it started working. I couldnt send picturemail until I asked someone to send me a picturemail me. I got no notification for the entire day...then I went to Send/Recieve within the Sprint Picture Mail Inbox a few hours after the pic was sent and my Diamond took a long time to initialize everything but in the end I successfully recieved the MMS.

Just to add, I had a Samsung Instinct before this with a Talk/Message/Data family plan so my account was already setup for Picture Mail. This could be the deciding factor. You guys may need to call Sprint about this as this could just be an account setup issue.