Just ran your script successfully, here are some thoughts:

Even after I uninstalled all my pip packages with the command you suggest, I had to rm -rf pip 6.0.8 from my /Library/Python/2.7/site-packages/. Worthwhile to note that I'm using pip version 7, so I'm not sure what that file was doing in there anyways–I wasn't using it in any case. Maybe implement a way to check which pip the user is using (via $(which pip) or something) to reduce the amount of pre-install surgery that needs to be done by the user.

Homebrew told me opencv-2.4.11_1 (current brew opencv version is listed as 2.4) was already installed and that I would have to unlink it. I decided to instead uncomment that requirement in your script.

After all rosdeps are installed successfully, script asks me for password, doesn't tell me why beforehand (I believe it is for catkin building).

Why install the the sourcing script in /opt? My personal preference would be to keep this file in the same directories that are used to build everything.

Cheers,

Nils