A very nice writeup on httplib2, GData and the Atom Publishing Protocol by Jon Udell:
The hero of the piece is Joe Gregorio, whose wonderful Sparkline service I highlighted a while back. Joe is also, and rather more notably, the author of both the Atom Publishing Protocol and Python's httplib2 library, two projects that came together to facilitate my transfer of calendar data (see script below).
*Blush*. While I have been pushing for a RESTful publishing protocol for close to four years, I am an editor of the APP, which is really the result of a collaboration of a large group of very talented people in the Atompub Working Group.