<p>So the official XML-RPC standard doesn't support 64-bit values.  But in these modern times, 64-bit values are increasingly common.</p>

<p>How do you handle these?  What XML-RPC extensions are the most common?  What language bindings are there?  I'm especially interested in Python and C++, but all information is appreciated.</p>

I don't know anything about how XMLRPC could be extended but I did find
this mail
about the subject:
In XML-RPC, everything is transmitted
  as a string, so I don't think that
  choice is really that bad - except of
  course for the additional clumsiness
  for invoking explicit conversion
  functions.
But no, XML-RPC doesn't have a data
  type that can represent integers above
  2**32. If you can accept losing
  precision, you can use doubles (but
  you still would have to convert
  explicitly on the sender).