This script allows me to open IPython and other Jupyter notebooks directly from Finder. I use iTerm2 as my default terminal, so I took advantage of their AppleScript docs to write this. A big usability advantage is that no new terminal window is opened for the notebooks, just new tabs. This makes the whole process much more discreet and reduces window clutter.
In order to implement this, just save the script as a new application in Automator. Then make the application the default application for the .ipynb extension.