Apple has released two new Bonjour (mDNSResponder) releases to coincide with the OS X 10.7.2 sources. The releases contain the source from OS X 10.7.2 plus important bug fixes for Posix and Windows. 

OS X 10.7.2: mDNSResponder-320.10 (tarball)

Posix: mDNSResponder-320.10.80 (tarball)

Windows: mDNSResponder-333.10 (tarball)

You can learn about Bonjour and other open source technologies at developer.apple.com/opensource.