Presence & Tagging

I want to add centralized tagging to the centralized buddy list of an instant message server. Perhaps personal tagging would be useful but let's start by helping everyone. By tagging a buddy I mean to place them in a group, a team, a project, a location, a department, a title, an interest, etc. My office tags might be
Andrew Gilmartin:
Principle Engineer, Engineering Team, Providence, RI, USA, Narragansett Project, AlphaDog Project, BetaBand Project, Stewie Project, Java Specialty, Concurrency Specialty, User Interface Specialty, Data Model Specialty, Interface Specialty, Gardening Interest, Cooking Interest, Parenting Interest, Board Game Interest, Automata Interest, etc...

My instant message client user interface would then allow me to view staff by any set of tags. Either a small faceted search or a two-level hierarchy. Selecting an account name would start or join a conversation. Selecting a tag would start or join a conference.