How to install Node.js on Ubuntu via git

$ sudo apt-get install git-core python libssl-dev build-essential
$ git clone git://github.com/joyent/node.git node && cd node
$ git checkout vX.Y.Z

Check the latest stable version on https://github.com/joyent/node/tags
v0.8.8 at the moment

$ ./configure
$ make (it will take some time)
$ sudo make install

Do a check with:

$ node -v
$ npm -v

A new version came out?

$ git pull

then checkout and install the new version.