XMLSIG For Dynamic Languages is a sourceforge hosted project sponsored by Verisign developing code providing xml digital signature libraries for scripting languages, including in particular Python. Wish we had this a few years ago for an XML product we were building.
I've started looking through the code and its pretty solid. I suppose the next step is to install it and build a Python app or two to see how easy it is to work with. I can think of a couple of fun things to do.
This will make it easier to develop SAML-based apps in Python.