Startup Idea : Mobile app called as mobile projector

All smart phones have access to youtube,video access,document access.In this scenario having a projector inbuilt in a smart phone would be a plus.During a meeting one can project a ppt slide on the wall and conduct a full fledged presentation.One can watch a downloaded video on a big screen via mobile projector.There are few cell phones which have inbuilt projector, there are mini projectors also available eg 3M has one.But why not make an app which will use the existing cam on the phone as a projector.