Comment 2 for bug 592600

I think any extensions from inside /usr/share/zeitgeist/_zeitgeist/engine/extensions/ and ~/.local/share/zeitgeist/extensions/ should be loaded by default (or if you prefer, those symlinked in a "active"/"default"/whatever directory within those directories). The ZEITGEIST_DEFAULT_EXTENSIONS variable would only be there for the user to disable some of those (plus we should also add a ZEITGEIST_DISABLED_EXTENSIONS var).