I released Mono.Zeroconf 0.7.4 last night which is a minor bug fix release. Packages are available for openSUSE, SUSE Linux Enterprise, and Fedora. Sources and binaries are available for Linux, Windows and OS X.
I started working on Mono/.NET bindings to Bonjour/mDNSResponder almost two years ago. The code was quite useful but we found ourselves adding a lot of nasty preprocessor directives -- yes, in C# -- and configure junk to support both Mono.Zeroconf (Bonjour) and Avahi in software like daap-sharp and Banshee.