HTC just tweeted that EVO 4G users who downloaded the unofficial Froyo build but for whatever inexplicable reason have not yet manually upgraded to the official build will be getting it via an OTA update, starting today. I appreciate HTC’s dedication here, but I think this probably the smallest target device group for an OTA ever.
If you’re still on the unofficial version and can’t wait for the OTA update, you can download it directly here (read the instructions in this thread). It does require a little work (you need a PC and a USB cable), but isn’t by any means difficult. It is the same update package HTC is providing OTA.
And for you developer types, the source for the official EVO 4G 2.2 update (version 2.6.32) is now available for download direct from HTC.