While we were at BlackBerry 10 Jam 2012 in Orlando RIM mentioned that they will be replacing the BlackBerry 10 Dev Alpha devices they were distributing. The catch was you had to submit a BlackBerry 10 app to App World and then you were eligible for a special edition BlackBerry 10 device at launch. Lucas @N4BB received confirmation from RIM again that they will be disabling the BlackBerry 10 Dev Alpha devices after the launch of BlackBerry 10 when it will automatically brick itself. As RIM promised before you can then send it in for your replacement BlackBerry 10 Special Edition device if you have an app accepted in App World.
Lucas did hear that the BlackBerry London is an earlier revision of the BlackBerry 10 final hardware and is what RIM will be giving out as a working special edition BlackBerry 10 device. I Think that would be a pretty sweet deal though personally I like the softer edges of current BlackBerry devices.