Since HTC made the announcement that it would be bringing Gingerbread to the HTC Desire (minus some applications) they've been letting owners know where the update's at in testing. Most recently, HTC updated its Facebook page with the following details:
Hi everyone. We have more news about our build of Gingerbread for Desire. Our testing has gone well so we will begin rolling out the update by the end of July! Thank you again for your support!
There you have it, not an exact date but close enough to keep everyone in the loop and you can't really as much more then that.