For those that used Unrevoked3 with 2.1 and can't get the OTA install to work, try this one from Pojoman at xda:
Pojoman vs. HTC - The race of the "delayed" 2.2 software fix. - xda-developers
Cliff notes version:
YOU WILL LOSE ALL DATA ON THE PHONE (not the SD card, just the internal phone memory), this is a wipe of your phone.
Download:
RUU_SuperSonic_S_Sprint_WWE_3.26.651.6_Radio_2.15.00.07.28_NV_1.40_release_140444_signed.exe (note: it is 193 MB (202,577,431 bytes))
1. Install HTCSync
2. Press down and power simultaneously, and go to the bootloader
3. Allow the hboot to run.
4. Connect the usb (note: make sure you allowed for usb debugging prior to loading bootloader)
5. Press fastboot (Using the power button as select) and it will change to Fastboot usb
6. Run the .exe from your computer.
7.Thank Pojoman and all those who talked him through the day while waiting for this fix.
Took me about 15 min, but worked. Updated to 2.2 on a previously 2.1 running Unrevoked3. you
WILL lose superuser/root.
Hope this helps some of you stuck at the <!> point. Remember to thank Pojoman for his work getting this one.