For educational purpose, the built-in sort() should be faster.
{{{
>>> def qs(l):
...     if len(l) <= 1: return l
...     return qs( [x for x in l[1:] if x < l[0]] ) + l[:1] + qs( [x for x in l[1:] if x >= l[0] ] )
>>> l = [random.randint(-100,100) for x in range(10)]
>>> qs(l)
[-73, -59, -27, -17, -12, 16, 22, 40, 53, 83]
>>> l.sort()
>>> l
[-73, -59, -27, -17, -12, 16, 22, 40, 53, 83]
}}}

One line quick sort (Python 2.5 only)
{{{
qs = lambda l : l if len(l) <= 0 else qs([x for x in l[1:] if x < l[0]]) + l[:1] + qs([x for x in l[1:] if x >= l[0]]
}}}

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CategoryCookbook