While X.Org has been uploaded to Ubuntu’s ‘Hoary’, native Debian packages will not be introduced until Sarge is released, and like every Debian release, this may take a while. For Ubuntu is based on Debian and the packages are maintained by Daniel Stone and his colleagues, why not try some distribution-mixing?
I posted some hints on this in the Unofficial Debian User Forums and wrote a more detailed, but german description which can be found at debianforum.de.
For those who don’t want to fiddle around with their running XFree86 installation, Steve Smith wrote a description how to install a non-intrusive X.org server from source.