“No one has an incentive to deliver that upgrade to you. Google is interested in new handset activation, the handset makers have sold you a phone and hope to never hear from you again, and the carriers have you hooked up to a multi-year ball-and-chain.”
So why waiting?!
There is already ICS build for Htc Desire. It still Beta v0.1.4 and many features are not working but it is improving quite fast and I can tell you it is working very well also. I have been testing since 0.1.1 and the current build seems to work quite well.
You can find the download link and some more info here: http://forum.xda-developers.com/showthread.php?t=1355660
Download, boot to recovery and flash the image – 3 small steps but gather a lot more independacy from Google, Htc and you carrier.