The peeps over at PhanDroid have reported that HTC have already announced an OTA Firmware Update is available for the HTC Desire. Some people in the forums have been trying to get the update to install but it sounds like only the people with unlocked phones are able to get it. Those of you who purchased your phone from T-Mobile UK will have to wait for T-Mobile themselves to push out the update.
From HTC:
In our commitment to providing you with the best user experience, we are pushing out a new firmware update to your phone. Your phone will receive a notification of this update when it is made available. Simply press OK to accept the update via a data connection such as Wi-Fi or GPRS/3G. After installing the update, you can confirm a successful update by confirming the Software Number (From the Home Screen go to MENU> Settings> About Phone> Software information> Software number). The new software number after the update will be 1.15.405.4 for an HTC phone.
Note: We recommend using a free Wi-Fi hotspot or an unlimited data plan to apply this update. If not, standard data connection charges may apply. For any questions, please contact us at http://www.htc.com/www/CA_Hotline.aspx
The people who have managed to get it installed are reporting that they can see no differences or performance improvements so maybe it’s only some background bug fixes that we don’t even know about yet.
Source: PhanDroid