It only recently we were talking about how the number of developer devices in the wild for Windows Phone 7 was just eeking past 3,000.
While seemingly impressive, it was a drop in the bucket compared to the number of developers who need a device.
Well, if the latest Facebook registration numbers are to be believed, that number has doubled and is now at roughly 6,483--pretty impressive. How high will it go? We have no idea, but at least we know Microsoft is trying to seed these devices as quickly as possible.
Edit: Or as Matthew Miller (Nokia Experts) notes in comments, instead of 6.000+ phones, perhaps we're looking at the same 3,000 but in new hands as developer/tech preview units have had to be returned.