About 15 days ago, only 3 days after the new android version (Ice Cream Sandwich (Android 4.0)) was released, the XDA Android community started developing a ROM for the HTC Desire. Since it is not likely for HTC to release an official ROM for this device, this community developed ROM will be the only chance for the HTC Desire users to taste the newest version of Android OS.
In the process of building this ROM, two main problems appeared, making the camera work and making the newly introduced Hardware Acceleration work. Since HW Accel. is one of the best features of the ICS it was of great importance this feature to be available on the HTC Desire. HW acceleration is working on the newest version of this XDA ROM, and the only thing that is making this ROM not usable for a everyday use is making the camera work. I suggest you try this ROM, its fairly stable and it brings all the benefits of the newest Android 4.0.1 Ice Cream Sandwich.
Here, you can see a video with of HTC Desire running the newst version of the ICS ROM.