yes the ubuntu help is outdated. Java is now owned by Orace and distributions are not allowed to carry newer releases in their repositories.
Though it is still provided for natty, so i added the natty canonical partner repo to the sources.list
Add this at the bottom:
sudo gedit /etc/apt/sources.list
now save the file & close the text editor. Back in the terminal:
now you can disable the natty partner repository again. (just place a # at the beginning of the deb line
sudo apt-get update
sudo apt-get install sun-java6-jre