Okay, I signed up. I'll be getting an e-mail and text message as soon as Barack Obama announces his pick for vice president. In fact, I might have already received it by the time you read this. However, I didn't sign up because I needed to be "the first to know," as Obama's Web site touted last week. Instead, this was a trailblazing marketing moment — the first time that a presidential campaign has used mobile and e-mail marketing in this way — so I wanted to see what the fuss was all about.