Check where a program comes from. Check what it's trying to do by watching the way it accesses data and other programs. Alert the user if something's going on that doesn't seem right or can be dangerous. Think about the implications of connecting systems together. It's a lot of work, and work that frequently doesn't get done because to the user, a system that's entirely secure looks and feels much like one that's riddled with holes.
Good security is invisible in normal use.
So the first stage is for the industry to establish a solid set of guidelines and a stamp of approval. If they don't want to do that, it might be appropriate for legislation to be thought about - but that shouldn't be necessary. Let's get a mobile data security forum convened. Look at what Sun did with Java. Get Microsoft, Symbian, Palm, whoever fancies carrying the torch for Linux, and everyone else in, and build that framework for secure personal communications devices.