When I setup a continuous location-updater I have to think about the actions of my future self. How can I guard against him? What if there are places or times that I do not want revealed (shopping for a birthday present, my home, etc.)? I take care of this by usually only sharing my neighborhood (it’s useful for both locals and non-locals without getting too specific).
However, in the future I’d like time-based rules (share specific places after 5PM), white lists (always share bars or when I am in San Francisco) and black-lists (never share my home). Services like Clarke and Fire Eagle and Latitude will need to add these safeguards before they get wide spread adoption.