since there was no date for the Desire HD ICS Update I asked the German HTC support if they have a specific date for the Update.
You can find the Answer in the attechment and for everyone who is not that into the German language here the translation:
Thank you for your request related to your HTC Desire HD
We only have the confirmation that it will roll out this year. But there is no specific date when it will happen. Our experts predict, it wont be later than August and expect it more likely happen in May.
[Standart things about to contact them again and a link to survey]