HTC Desire was just recently announced, and its ROM is already being ported into the Google Nexus One!
An alpha version of the ROM (with Android 2.1) is now available including the newest HTC Sence interface
and Flash 10.1 for Android and lots of widgets for the HTC Sense experience.

[youtube]http://www.youtube.com/watch?v=tL60j3iDgLk&feature=player_embedded
[/youtube]

Follow the step by step guide (at your own risk) to get HTC Sense from HTC Desire up and running on Google Nexus One phone.