make sure you've got maemo extras enabled,

then you should be able to do an:

apt-get install python2.5

What I usually do to install python is install Canola2 (my favorite media player) because it depends on Python and a bunch of its modules

Or, if you don't like canola, youamp, pygtkeditor, and all of the home-applets depend on python as well.

EDIT: I thought of a better idea. Install the Python Launcher from the application manager. It (obviously) installs python, and also speeds up launch times for python based applications