How to keep up with the latest versions of Node.js in Ubuntu? PPA? Compiling?

Most up-to-date ppa for nodejs https://launchpad.net/~chris-lea/+archive/node.js/

sudo add-apt-repository ppa:chris-lea/node.js  
sudo apt-get update  
sudo apt-get install nodejs

NOTE: If your system does not have add-apt-repository, it can be installed like so:

sudo apt-get install python-software-properties

I'm the maintainer of the PPA listed above. I actually maintain three distinct Node PPAs:

https://launchpad.net/~chris-lea/+archive/node.js https://launchpad.net/~chris-lea/+archive/node.js-devel https://launchpad.net/~chris-lea/+archive/node.js-legacy

They contain the current release, the development release, and the "previous stable line" respectively. Here's some more info on using them:

https://chrislea.com/2013/03/15/upgrading-from-node-js-0-8-x-to-0-10-0-from-my-ppa/

I currently intend to keep maintaining these unless the Joyent folks start maintaining their own repositories. They have me on IM so I'm generally quite aware of when new releases are coming out, and I try to put up new builds within a day of the source code being available.