Very cool! Reminds me of the games I was programming as a teen. Pygame seems like a pretty straight forward framework to easily start seeing things move on the screen which is really important to keep people motivated.
It's a bit confusing that near the beginning it says that on a Mac Python is already installed (yay!), but as soon as you get to the meat where PyGame is installed, it basically says you'll need to re-install Python if you're on a Mac. So the "already installed" bit isn't all that useful, or did I misread?
I think what he's trying to say is that the Mac already has a preinstalled version of python which would allow you to get started and programming right away, however if you want to install pygame you would need to install a newer version of python which is more complete.
Yeah, sorry. I've learned a bit since I wrote that, my new tutorial is coming out and it explains installing PyGame and Python on both Mac and Windows.