Ben Brooks and alert overload:
This is a really tough problem to solve for Apple, but I think we can be assured they are working on it. If evidenced by Messages on the Mac alone. When you are iMessageing you don’t get alerts on all your devices under very particular circumstances — that’s Apple’s acknowledgment of the annoyance factor that comes from multiple alerts.
This is the kind of thing Apple likes to do. Take a long standing problem and solve it. They made the best touch device anyone had ever used, and I am expecting big things in Mountain Lion and iOS 6 on this front.