1. IP and Privacy/Data Protection.
2. Regulatory Issues (e.g. location data, premium - rate/pay-by-phone services and dealing with App Stores - term/commercials (%share taken).
3. Issues regarding contracting on the move - incorporation of commercial terms and limitations/exclusions in particular (will customers actually read your terms when on the move) and commercial issues when building apps for other people (e.g. ownership of end result, interfacing with API's, project scoping etc).