Converting a string to an array?

[Tim Chase]

While working on a Jumble-esque program, I was trying to get a 
string into a character array.  Unfortunately, it seems to choke 
on the following

	import random
	s = "abcefg"
	random.shuffle(s)

returning

   File "/usr/lib/python2.3/random.py", line 250, in shuffle
     x[i], x[j] = x[j], x[i]
   TypeError: object doesn't support item assignment

The closest hack I could come up with was

	import random
	s = "abcdefg"
	a = []
	a.extend(s)
	random.shuffle(a)
	s = "".join(a)

This lacks the beauty of most python code, and clearly feels like 
there's somethign I'm missing.  Is there some method or function 
I've overlooked that would convert a string to an array with less 
song-and-dance?  Thanks,

-tim