gistfile1.py

import string
import sys

def perms(s):
    letter_map = [c in string.letters for c in s]
    num_letters = sum(letter_map)
    num_perms = 2**num_letters

    for perm in xrange(num_perms):
        letter_perms = [
            c.swapcase() if (1 << i & perm) else c
            for i, c in enumerate(c for c in reversed(s) if c in string.letters)
        ]
        yield ''.join(
            letter_perms.pop() if is_letter else s[i]
            for i, is_letter in enumerate(letter_map)
        )

for perm in perms(sys.argv[1]):
    print perm