If, like me, you had to import your Desire from overseas, you will still be waiting for the 2.2 FroYo update on your Desire.
Having played around with my phones for a while now, I was curious as to whether there was a method to flash it via ROM, because the OTA (Over the Air) update's not available in New Zealand (then again, nor is the phone according to the HTC site.

)
**DISCLAIMER**
I followed these steps and my phone successfully flashed to FroYo 2.2.
If something goes wrong with your phone,
I can accept no responsibility
Remember to backup your data before you start, and if you are unfamiliar with flashing ROMs, read up on that too.
Root access is not required, but will be lost if you perform this update.
In essence, the steps below walk you through:
- Creating a 'Gold Card' to debrand your phone (you will need a 2GB SD card)
- Installing HTC Sync
- Flashing a World Wide English version of Sense to Downgrade to a lower version than the Desire shipped with
- Flashing the 2.2 FroYo ROM
...