Piper Jaffray’s Gene Munster estimated that by midnight Sunday, Apple will have sold 600,000 to 700,000 iPads, including pre-orders — more than double his relatively conservative pre-launch estimate of 200,000 to 300,000, reports “Fortune” (http://brainstormtech.blogs.fortune.cnn.com/2010/04/04/new-ipad-launch-day-estimate-600000-700000-sold/?section=money_topstories&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2Fmoney_topstories+%28Top+Stories%29).

Other analysts had published estimates of 300,000 to 400,000. It took Apple 74 days to sell its first million units of the original iPhone, and three days each to sell a million units of the iPhone 3G and the iPhone 3Gs.