We've been (finally) getting Concordance's C code refactored into a standalone XMPP server called GNation.
Concordance used a good deal of GLib code already, but we've gone a bit further in using the GIO library for managing sockets and connections. In doing so, we were able to reduce roughly 160 lines of code for opening and monitoring listening sockets into 12 and I suspect further reductions as we continue. All of the IPv4 vs IPv6 support was cleanly abstracted, adding a socket listener to the MainLoop was done automatically, and the GIO documentation was of the same high quality we've come to expect from GLib.
Major thanks to the hard work that has gone into this!