Xpertmud is where most of my open source activities take place. Xpertmud is a gui for text mud clients, which is highly scriptable. Scripts are implemented as plugins, so everybody can write new engines. At the moment perl and python scripting engines are implemented. The feature which makes Xpertmud better than other mud clients is that all communication with the server can be accessed in a script (no parsing is done in C++ code). A plugin interface for gui elements exists and Xpertmud is has found it's place in life for battletech muxers.
Today I found a discussion thread about some xpertmud features.
Xpertmud development is rather slow at the moment, I'm trying to keep up to the upcoming KDE 4.0 development which will enable us to release a KDE based xpertmud on Windows.
The best place to get more information about Xpertmud is the BattletechMUX docmentation Wiki, especially the Xpertmud Getting Started Guide.