Some stores have already sold out of iPhone 4s before the end of the day. Nine of 20 Apple stores had already exhausted their stock in the morning, and all others are expected to clear theirs by the end of the day. Earlier iPhone launches have usually taken a full weekend before significant sellouts, so this is really saying something.
According to one analyst, assuming Apple reserved about half its total launch supply for those who hadn’t pre-ordered, we can expect to see at least one million and as many as 1.5 million iPhones sell this weekend. The low end would match Apple’s previous best sales, with the iPhone 3GS. They may just hit a new record.