I install ipython on Mac OS X Lion following this: How to install iPython on Snow Leopard
As I doing this on my Mac sudo /usr/bin/easy_install-2.6 python
Turns out I originally have easy_install-2.5, 2.6, 2.7 installed!
Then I choose easy_install-2.7 to install python, it works.
But what if I install ipython with 2.5, 2.6 version of easy_install? What's going on behind this?
It will install IPython for the different versions of Python installed on the system. Starting IPython for each version will bring up a shell for the appropriate version of Python.