Piper Jaffray analyst Gene Munster has substantially raised his iPad forecast for 2011, pushing it from 14.5 million to 21 million. Such is the tablet's success that it's in a position to outsell the Mac, the analyst argues. "We believe the iPad represents a meaningful product category for Apple as a secondary computing device for those who already have a primary computer, a primary device for those who could not previously afford a Mac, and the first Apple product that will be a success in the enterprise," he says.