A while back I wrote a post expressing a longing for wait-interface tuning like we have for Oracle (and now SQL Server, I hear). Since then I have found out that the MySQL community server (since 5.0.37) has something starting along those lines: the query profiler.
Using the query profiler, you can get at wait times for a particular query, to help you tune it. There is the official documentation, and, even better, an article by Robin Schumacher that explains and gives examples.
From here it would probably be a “simple” matter to start collecting all this data system-wide, into a repository, to gather global information on wait-event times. In the meantime, this is certainly a step in the right direction.