Installed additional python2.7 to Snow Leopard. What happens to modules I want to install?
Install of python modules goes in x/Library/FrameworksPython.framework/Versions/2.6 etc where x depends on the install.

nothing for the one from Apple as port of OSX. python executable in /usr/bin

nothing for pythons from python.org. python executable in /usr/local/bin

/opt/local if installed via macports (as I do)

You have to look at easy_install etc to see the path to the python they use. e.g. /usr/bin/easy_install has /usr/bin/python so using this will install in /Library/FrameworksPython.framework/Versions/2.6.

You cannot choose to run under a minor version of  python e.g. 2.7.2 as only one major version at a time is set up normally e.g. 2.7.2 replaced 2.7.1
Each major version of python will have its own executable e.g. python2.7 s to have a script use that verstio make it begin with #!/usr/bin/env python2.7 pr the full path.