http://o2s.csail.mit.edu/download/pybonjour/

pybonjour provides a pure-Python interface (via ctypes) to Apple
Bonjour and compatible DNS-SD libraries (such as Avahi).  It allows
Python scripts to take advantage of Zero Configuration Networking
(Zeroconf) to register, discover, and resolve services on both local
and wide-area networks.  Since pybonjour is implemented in pure
Python, scripts that use it can easily be ported to Mac OS X, Windows,
Linux, and other systems that run Bonjour.

pybonjour 1.1.1 includes the following changes:

* All DNS-SD API calls are now made after acquiring a global lock
   object.  This object is a dummy (i.e. acquire() and release() do
   nothing), except in the case where pybonjour is using Avahi's
   Bonjour compatibility layer, in which case the lock is a
   threading.RLock instance.  This is necessary because the
   compatibility layer is not thread safe.

* Added browse_resolve_query.py to examples

For more information, see

   http://o2s.csail.mit.edu/o2s-wiki/pybonjour