Open source networking platform Elgg has been used in CET for some time now, probably since version 1.1. Several successful projects are still running on it and future plans are promising. Although for most of the project Elgg is providing stabile platform for prototyping, one of the live-sites running on Elgg has over 1500 registered users and as a platform it has proven its strengths.
For my own personal reasons I’ve been working on usable (and visually clean) Elgg theme that could be use as a starting point for developing a new theme. Elgg Blank is clean theme for Elgg 1.7.2, tested on Firefox 3.5 and latest Safari. Doing my best to test it on IE 8.
Do not hesitate to give any feedback on it. Checkoutl the latest Elgg Blank from here.