Crestron has an app for that!  The Crestron Mobile Pro app found in the iTunes App store can be downloaded to an iPhone, iPhone 3G, and the iPod touch.  It uses two different ways to communicate with your home automation system.  The first and possibly more robust way is using the 3G network.  This means that you can check the status of your lights in the bathroom from anywhere in the continental US (try not to remember the lack of coverage offered by AT&T)  The second way is using your home wi-fi network or a hotspot at your local Starbucks.  Both of these connections have their own pros and cons.  Without some extensive testing, I will not be able to comment on the response time of the button presses through either of these connections.  I hope to see it in action in the wild soon so more to follow.