Well I just posted the previous and up popped a site with the source and binaries for a Remote Desktop that is built on AJAX, JSON and HTML5. It is also listed as GPL3.
URL: http://www.codeproject.com/KB/IP/ThinVnc2.aspx
With Wayland in the future in several distro's (Red Hat and Ubuntu & derivatives) are technologies like this something that could be used in an x2go future?