With the proliferation of 2G and 3G Telecom and other wireless networks hundred of millions of users will be able to access wireless services with their terminals in only a few years. In this paper we discuss the possibilities and limitations of existing and emerging mobile technologies and methodologies for porting information and functionality from traditional PCs to mobile devices and vice versa. We argue that in order to be able to properly port things between devices an equivalence concept for user interfaces is required.