When you install a new Python module on your computer, all stuff will be copy in /Library/Frameworks/Python.framework/versions/2.5/ (or equivalent in Win computers) so if you set Python Interpreter (Eclispe>Preferences>PyDev>Interpreter Python) in Eclipse or Aptana in bin folder of this path you can find all new module when you work with those IDE.
But if you set a couple of folder before like /Library/Frameworks/Python.framework/versions/2.5/ you can find everything you need to work with new Python modules.