I recently needed to manually assemble and send some syslog packets directly from Python and didn't find anything else that fitted my needs. So I read the RFC and wrote a module to do it. It was surprisingly straightforward, though writing the tests first definitely helped.
I've not released it yet (I'm looking for some peer review on the API first), but I think it's pretty much ready for it's frist release. You'll find it at at http://hacksaw.sourceforge.net/netsyslog/.
Feedback on the API would be much appreciated.