The smartphone market had been around for years and was growing.
By late 2006, over 100 million smartphones were being sold annually worldwide. The introduction of the iPhone in 2007 made barely a blip on the smartphone market's growth rate. A radical increase in sales didn't happen until affordable Android phones came out.
All those preceding smartphones were the reason why carriers worldwide had data networks. And why Google was able to provide smartphone crowd-sourced cell tower positioning for the initially GPS-less iPhone. And mobile search and maps, which other smartphones already had.
This ready made smartphone infrastructure and market is why Apple wanted (and was able) to jump in, albeit years late. Apple rarely invents a product. They wait until the infrastructure and manufacturing and chips and consumers are all hitting the right notes, and then jump in with something not held back by legacy issues (at least, not at first).
True, at least from a major consumer electronic company. Smaller companies had made finger friendly UIs before, with orientation sensors, and had even announced pinch zoom, but few had paid attention because they were not as well known as Apple.
Interestingly, 2007 was the year that several analysts had predicted that capacitive touchscreen finger friendly phones would become popular. That, plus public demos and concepts of such smartphones, is undoubtedly what made Jobs break secrecy and show off the iPhone a half year before it was ready for sale, using prototypes that couldn't even work for more than a few minutes at a time.
As others have pointed out, people outside the US had better smartphones for a long time. They were already doing video calling over 3G, for example.