If you have the following directory structure:
|_ github_projects |_ rails |_ vimfiles |_ devise |_ redmine |_ (and thousands of other opensource projects)
You can update the repository of all your projects with one command =)
Run the file with the command
git clone git://github.com/lerrua/update_repos.git cd update_repos
And finally
. update_repos.sh
Thanks to @joaovitor for the inital code.