Why not usage tracking in BIPublisher 10g by adding simple log statements.
date|userid|reportpath|started
date|userid|reportpath|completed
I agree, lot people will request more details once provided with simple things but something is better than nothing. Now we really believe in Apache logs and REUI which needs bigger setup and time consuming. If its in log simple grep will help in diagonising following pretty easily, now there is no way ( otherthan cumbersome debug mode which requires restart and its very extensive)