Previous rumors had the iPhone 5 release date pegged for the third or fourth week of September, and a new report appears to confirm, going a step further and marking the date of September 21.
TechCrunch reporter Jordan Crook cites a "trusted Verizon employee" as confirming that the company is having an all-staff vacation blackout from that date through the 30th, and that the 21st - a Friday - is indeed the launch date.
Apple is expected to unveil the device on September 12 (likely without the actual "iPhone 5" name), as the company has been said to have an event planned for that day. As Crook points out, the timeline would fall in line with last year's release of the iPhone 4S (though that was in October).
As far as the release date, we'll leave it in the "rumor" file, as nothing official has been revealed yet, but I'd say this one has a pretty good shot at being legit.