@timbrandin’s one here looks like the most current. I’ll try to give some feedback on it soon - I can envision using it to build an NPM package that can be used inside Meteor, by declaring Tracker as a peerDependency.
I think it should be tested in both client and server capacities, but since it’s not a library intend to span client and server it need not be built as an atmosphere library and bound to the Meteor package repo, when npm is clearly the larger ecosystem.