Ever since I got a Droid I have been literally amazed by how much a smartphone can increase your productivity, keep you in touch with news as well as contacts, and introduce you to new ideas and products. (I have seen the iPad but not tried it and am sure its the same).
Marketers who want to build a relationship with their customers and keep it strong would do well to think about offering them access to this technology. Special populations to target I think are those who tend to lag in adopting technology due to cost or perceived difficulty.
Give people the tools to empower themselves, and they will reward you with continued loyalty - that is my hypothesis. You can do well by doing good.