The International Telecommunication Union(ITU)have a report online due in September 2004,entitled “The Portable Internet”.A preview of the report can be had below with sample pages in pdf available.From one of those pages.”Identifying the market opportunity for the portable Internet.The potential worldwide market opportunity for portable Internet technologies, over the next ten years or so,might be segmented into three blocks of potential users, each composed of around two-thirds of a billion people, making two billion in total.”
ITU Internet Reports 2004:The Portable Internet