Compared to everything that has gone before, the introduction of smart phones is more important, because it spreads computing power to a much larger user base. How has this fundamentally changed our relationship to the technology.
What social or economic forces are driving the process?
Smart phones are important because they combine three of the most significant technological advances of the past 20 years into a single device, the internet, the miniaturization of high speed computing power, and the portability of both. You are correct that smart phones make computers accessible to more people in more places than ever before. This has changed our relationship with technology in that now we can utilize it in almost every aspect of our daily lives. Before, we had to schedule time for computer based activities because they were not mobile objects. We had to take the time from other things and make the effort to come to them. But now we don't have to delineate between the two anymore. We can take the computers with us throughout our daily lives. And as a result, we can use them in ways we wouldn't have even just a few years ago. For many people, smart phones can now be used in place of going to the bank, using the post office, or going to the store. You can grocery shop online is some places. You can even use them in place of a telephone (mobile email, texting, instant messaging), one of the uses they were originally invented for!
There are both social and economic forces as work here. Clearly our society demands these products as evidenced by the fact that they sell so well. People like affordable technology and are willing to pay for it to be able to incorporate it into their daily lives. But make no mistake that smart phones are also big business. Technology companies did not invest large sums of money into the development of these technologies just for fun. They expect to make a profit on their investment. So smart phones are a great example of social and economic forces coinciding nicely in a single product.