The problem is currently GUI. There are no good GUI's to work with git. Windows and Mac OS X have some GUI tools scratching the surface of what's possible with git, but none come close in opening up the full possibilities of git. Linux has a few very alpha, specific (like showing branches) GUI tools.
If we want non-programmers to use git, we need GUI's to instantly visualize the state, commands and other possibilities. No non-programmer is going to learn git using a CLI.
I think that github is such a good tool to interact with git repos that if they made a version that can work locally (the main difference is explicitly dealing with the index and the current tree) I'd use it to manage git projects in a heartbeat.
If we want non-programmers to use git, we need GUI's to instantly visualize the state, commands and other possibilities. No non-programmer is going to learn git using a CLI.