Apache has cross-platform logging libraries, which allow you to log from various programming languages using similar APIs. Unfortunately they don't have a Python API, though you should be able to whip one up with log4cpp and Boost.Python.
A project I work on uses one of these libraries to log to a database, which allows us "distributed logging" with a centralized place for the log messages. I have to admit I'm not a fan of this. Another project I work on uses one of these libraries to log to the native logging facility. The Windows Event Log has some features for distributed logging, but AFAIK syslog does not.
Although I don't have any experience with it, a better fit may be Facebook's Scribe project. The feature set meets your requirements, including a Python API. Unfortunately it uses Thrift which doesn't work for C++ on Windows (that is, the Thrift compiler generates C++ code that only works on UNIX). You may be able to get around this problem using Cygwin, but I can't promise that approach will work.