A word on short messaging -Regardless of SMS or MMS or Tweets, messaging is the best channel for notification-like distribution. Second to none. True SMS is way to expensive and prohibitive for many. SMS though is a cash-cow for network providers who must be terrified of Twitter. If targeting notification-like app such as promotions, SMS and Twitter is the way to go.

On Coding: Messaging, Multimedia Messaging on Java ME

Good External Resources