New network technologies are often challenged with the question: "What is the 'killer application'?" and, similarly, new application technologies face the question: "Where will this be used?" We won't pretend to know the answers to these questions but, in pulling together the chapters for this book, we have tried to take a pragmatic view of two particular application technologies location and personalisation at a time when the world is charging towards the new network technologies of broadband and 3G.

Personalisation, although founded in the world of targeted marketing and on-line sales, has proven to be a key success factor in mobile telephones but not always so successful in the Internet world. Location-based services, meanwhile, were touted as the 'killer application' for upcoming and next-generation mobile data networks, but this has not yet proved to be the case. The limited display and on-the-move use of mobile devices lends itself to requesting services based on your current or intended location and the display of information relevant to your surroundings and personal requirements. Until recently, access to location data has been restricted, but with the release of this information to application developers providing that privacy is not abused and that billing models can be sustained there is huge potential revenue for application developers and network operators.

The plethora of applications developed are likely to be supported by a revenue share model and, with 45 million mobile users in the UK alone, of which at least 2 million already pay...