Found a helper, to work with GitHub from command line. All your need is Ruby (it is already included into the Mac OS X). This script should be downloaded into the PATH, and aliased as alias git=hub.

To use all features, you also have to add you username and GitHub's API token into the ~/.gitconfig:

[github]
    user = svetlyak40wt
    token = a-secret-token

Afterwards, you'll be able to make a quick fork of any GitHub project, for example, mine ForkFeed is a good candidate as it is useful for GitHub users too:

git clone svetlyak40wt/forkfeed
cd forkfeed
git fork

Have a fun!