HTC Desire HD and Desire Z are getting an OTA update to improve system performance and provide camera feature enhancements. The update build no. 1.84.720.3 [Desire HD], 1.82.720.1 [Desire Z] are rolling out now to the users.
Your phone will receive a notification of FOTA update when it is made available. Simply press OK to accept the update via a data connection such as Wi-Fi or GPRS/3G.
Related Links: HTC Support