It’s widely known that HTC usually needs “some” time to upgrade their devices to the latest Android version. Gingerbread for the HTC Desire showed this to us in a very cruel way. The reason for that issue is that HTC’s custom software (mostly HTC Sense) needs much time to get adapted to the new programming-guidelines and restrictions of, in this case, Ice Cream Sandwich.

Because Android is open source  , the community has access to its source code  and can therefor adjust the new Android version to their devices on their own – usually without the manufacturer’s custom software. Thanks to the  great community  - Ice Cream Sandwich got adapted to all HTC Desires. But beware – these are at the moment so called  “DEV BUILD”s or “developer builds”. That means these are only for very experienced users with rooted devices.

If you are one of these “advanced” users or even a developer you might want to look at following threads in the XDA-Forums.

• (old) HTC Desire: “[BETA 0.1.1][12.12.11]ICS for Desire”  - Thread
• HTC Desire Z: “[ROM][11/12/11][BETA 4r1.2]Desire S ICS AOSP PORT|STABLE|DD MATERIAL ” – Thread  
• HTC Desire S: “[ROM][DEC 7] Ice Cream Sandwich for Desire S [BETA4r1]” – Thread
• HTC Desire HD: [ROM][BETA IV] Ice Cream Sandwich for Desire HD | Beta build is online | Source port
• HTC Desire HD: [ROM]Cookies and Cream ICS | b16 kernel | super fast | video playback 

Nearly all of those ROMs are stable, but some features are missing / not working. Thanks to the great XDA-Community!

Keep in mind: Only use these builds if you have experience with Android developing. Use them on your own risk.