Cyanogen posted instructions and links on the xda-developers forum for adding multitouch capabilities to the Nexus One.

http://forum.xda-developers.com/showthread.php?t=621441
http://www.walyou.com/blog/2010/01/24/nexus-one-multitouch-browsing-hack/
http://wiki.cyanogenmod.com/index.php/Main_Page