I recently read an article at Mobile Marketing Watch wherein they touted the popularity of the DirectTV iPhone application. You can control your DirectTV DVR straight from your phone. Pretty cool. 

There are already some really unique applications that have been developed for the iPhone that relate to digital signage. The one that particularly comes to mind is the app developed by Stimulant. Stimulant's app integrates an iPhone with Microsoft Surface. The iPhone app is used as a virtual "x-ray" device for objects being displayed the Surface. Stimulant's development team spoke with Microsoft a bit about their development work with the Microsoft Surface. Interestingly, Stimulant is not being too biased and they are working to bring both Microsoft and Apple products and applications together to create some interesting buzz.