Heh. Visual Studio actually does keep track of all the TODOs in all the files in your project. It's the Task List window (View -> Other Windows -> Task List, or ctrl-alt-K).

Depends on trust. I've had an experience where old tickets documenting important architectural problems (e.g. SQL injection) were mass-closed as "probably obsolete" by managerial types.

I was very happy I left a TODO in the actual code calling out the problem, because I could find and reopen the wrongly-closed ticket.