As you mentioned, you can do a system call:

For Windows:

>>> import os
>>> clear = lambda: os.system('cls')
>>> clear()

For Linux it would be:

>>> import os
>>> clear = lambda: os.system('clear')
>>> clear()

here something handy that is a little more cross-platform

import os

def cls():
    os.system('cls' if os.name=='nt' else 'clear')

# now, to clear the screen
cls()

Well, here's a quick hack:

>>> clear = "\n" * 100
>>> print clear
>>> ...do some other stuff...
>>> print clear

Or to save some typing, put this file in your python search path:

# wiper.py
class Wipe(object):
    def __repr__(self):
        return '\n'*1000

wipe = Wipe()

Then you can do this from the interpreter all you like :)

>>> from wiper import wipe
>>> wipe
>>> wipe
>>> wipe