Paul Rubin points out that the security implications 
of using marshal and/or pickle aren't clear from the 
docs.  Assigning to Jeremy as he's more sensitive to 
such issues than I am; maybe Barry would like to get 
paranoid too <wink>.

A specific example:  the pickle docs say that pickle 
doesn't support code objects, and "at least this 
avoids the possibility of smuggling Trojan horses into 
a program".  However,

1) The marshal docs don't mention this vulnerability 
at all.

while

2) The pickle docs don't spell out possible dangers 
due to things pickle does that marshal doesn't (like 
importing modules, and running class constructors).