Hudson can be installed as a Debian package, which enables:
wget -O /tmp/key http://hudson-ci.org/debian/hudson-ci.org.key sudo apt-key add /tmp/key
Then install Hudson
wget -O /tmp/hudson.deb http://hudson-ci.org/latest/debian/hudson.deb sudo dpkg --install /tmp/hudson.deb
Once the package is installed, apt-get update; apt-get install hudson will update Hudson. See Wiki for more information.