The Gingerbread update for the HTC Desire Z is in its final testing phase right now, and the roll-out should begin at the end of the month, though some carriers will be getting it earlier than others. HTC does promise that it should be on all Desire Z devices by the end of July.
No word on when the official G2 Gingerbread update will be arriving, but it seems a bit strange that we'll be getting Gingerbread with Sense earlier than stock Gingerbread. After all, didn't people buy a phone with stock Android so they could receive updates faster?
source: Ubergizmo