Privacy. The combination of a distracted user and a small screen make communicating privacy choices really difficult on mobile platforms (phones and tablets). In addition with the ability for apps to do things like potentially log communications (voice and text) and geographic location developers need to careful about the collection and protection of the personal information they are collecting.

Privacy laws are pretty lax in the US but in Europe, Canada and much of Asia the story is different.

A service that can handle "privacy" would be very valuable and would probable get support from regulatory agencies around the world.