I just got my D2 yesterday and I am wondering the same thing. It's very hard going from the D1 where I hit enter and the message sends. Now I hit enter and close my phone out of habit. Is there anyway to set the enter button to do this?
I am glad that is not a "stock" attribute, because I would be on here trying to figure out how to undo it. I hated my BB Storm for doing that, I was constantly sending before I was finished "talking".