I recently came across a project which used GIT as a version control system. I am normally used that you can download the sourcode from a SVN subversion repository. GIT is just another version control system.
Like most other modern version control systems, Git gives each developer a local copy of the entire development history, and changes are copied from one such repository to another. These changes are imported as additional development branches, and can be merged in the same way as a locally developed branch. Repositories can be easily accessed via the efficient Git protocol (optionally wrapped in ssh for authentication and security) or simply using HTTP - you can publish your repository anywhere without any special webserver configuration required.
Installing GIT on Ubuntu is quite easy you can simply execute a apt-get install git-core to install it.