Though, for the average user, it's nice to be able to set up rules within the Hue and trigger them with a tap switch (or I presume that's how it works.) For customers of automation system produtcs like ours (www.charmedquark.com), there is much more interest in allowing the automation system to react to such things. Most all lighting systems support this kind of things for switches that aren't controlling an actual load directly, so that the user can use those switches to invoke actions within the automation system. The obvious reason for wanting to do that is that we can provide vastly broader control options, since we can control pretty much anything in the home.
It would be awfully nice if the Hue support some sort of async reporting mechanism, and could report such events. It would make the Hue system far more interesting to the automation world. We can currently control the Hue, and that's nice since it can be integrated into the user's automation solution. But going the other way would be very nice as well.
Obviously this raises some issues with a straight call/response interface. But you could have an option to maintain a persistent HTTP connection and send asynchronous HTTP responses for that kind of thing. As long as it's only enabled upon request from the control system, it would be backwards compatible.