This thread is for coordinating efforts in improving oscpack via a separate repository on github. Any improvements will be committed back to upstream oscpack.
I added a tag for the latest oscpack revision, and made it clear in the description that this is a temporary repo.
A tentative collection of issues to solve/improve:
Slowdown due to blocking UDP communication:
http://forum.openframeworks.cc/t/serious-slowdown-with-ofxosc-on-windows/7823/1
Broadcast messages, and multiple listeners on one port:
https://github.com/openframeworks/openFrameworks/issues/722
http://forum.openframeworks.cc/t/broadcasting-with-ofxosc/1625/0
Maybe find why ofxOsc does not seem to work on 64bit Ubuntu at first connect:
https://github.com/openframeworks/openFrameworks/issues/701
Anything else? Happy hacking! 
Great initiative!
I added multicast (not to be confused with broadcast!) support for mac and windows. I made a pull request.