If you're a Democrat (although Republicans will have similar experiences), don't be surprised if a canvasser knocks on your door in 2012 and, glancing at his iPhone, says, "Ms. Smith, thanks for your $50 donation four years ago--and for attending the Joneses' party on the environment. Care to call voters in Ohio to help reëlect President Obama? Oh, and your neighbor Mrs. Jensen couldn't get to the polls in 2008. Think you could give her a lift on Election Day?"

As you answer his questions, the canvasser will stroke his iPhone, and a campaign server will squirrel away your answers. Minutes later, you'll get an e-mail from the campaign: "Thanks, Ms. Smith, for promising to make calls in Ohio." If you click the link, up will pop a list of 10 Ohio voters whose answers to phone-bank callers in 2008 suggest that they wavered between McCain and Obama and were concerned about the environment. You might call them and--following a provided script--explain Obama's environmental record, ask for their views on several issues and candidates, and record their answers with mouse clicks on a Web interface.