I just wanted to write up a quick tutorial for installing Jenkins CI on modern flavours of Ubuntu.
There's two options, you can download a pre-prepped specific package and install using aptitude or synaptic, _or_ you can set-up an update site to ensure you're always notified of updates.
I prefer the latter and used the following steps:
$ wget -q -O - http://pkg.jenkins-ci.org/debian/jenkins-ci.org.key | sudo apt-key add -
$ sudo echo 'deb http://pkg.jenkins-ci.org/debian binary/' >> /etc/apt/sources.list
$ sudo apt-get update
$ sudo apt-get install jenkins
By default, the Jenkins packages attempt to start up a java web container running on port 8080. To change this, open up /etc/default/jenkins and look for the following:
# port for HTTP connector (default 8080; disable with -1)
HTTP_PORT=8080
Change the port number to whatever works for you and (re)start the service
$ sudo service jenkins restart