DIME and WS-Attachments are basically dead.

MTOM (SOAP Message Transmission Optimization Mechanism) has shown up on MSDN (xml messaging page), and DIME, SwA, and PASwA are marked as superseded.

I have seen some places describing MTOM as basically the same thing as XOP (XML-binary Optimized Packaging), not sure if that is true or whatever, but it seems the message is clear: DIME is yesterdays news.