More on the Obama text-message campaign:

[A]nnouncing Mr. Obama's running mate by text message has little to do with proclaiming the selection and everything to do with getting out the vote on Election Day in November. The move should add thousands -- and more likely tens or hundreds of thousands -- of cellphone numbers to what is already one of the most detailed political databases ever created.

A study conducted during the 2006 elections showed that text-message reminders helped increase turnout among new voters by four percentage points, at a cost of only $1.56 per vote -- much cheaper than the $20 or $30 per vote that the offline work of door-to-door canvassing or phone banking costs.