'decompyle' converts Python byte-code back into equivalent Python source.
It accepts byte-code from any Python version starting with 1.5 up to 2.2
The generated source is very readable: docstrings, lists, tuples and
hashes get pretty-printed.
'decompyle' may also verify the equivalence of the generated source by
compiling it and comparing both byte-codes.

WWW: http://www.goebel-consult.de/decompyle/