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Yes this is a core feature of iOS for Enterprise Customers who wish to distribute OTA.
Presumably you would pass your UDID over to TestFlight along with the app and they use their Enterprise Licence to send the app to you. I'm sure I'm missing a lot of the technical details but if you want to know more, Apple has a video on this from WWDC 2010.
Login to developer.apple.com, go to WWDC 2010 Videos and use the link to get to the vidoes. The video you want is "Session 108 - Managing Mobile Devices". It is very informative about what is possible with OTA and the steps you have to take to do OTA provisioning.