Cupertino, Calif.-based gadget maker's tablet computer selling fast. Apple sold between 600,000 and 700,000 iPads during the tablet computer's first day of sales Saturday, Piper Jaffray analyst Gene Munster wrote in a note to investors Saturday. That's up from the range of between 200,000 to 300,000 units Munster had predicted earlier. Munster cited "longer than expected lines" and good iPad availability ...