From the Obama campaign comes the news that the VP may be announced by text message. I've found the page on Obamas website.
Be the First to Know
Barack is about to choose a running mate, and he wants you to know first. You have helped build this movement from the bottom up, and Barack wants you to be part of this important moment.
Sign up today and we'll send you an email announcing Barack's running mate.
Also an aricle in the La Times gives more detail.
Obama's VP choice imminent via website, e-mail, text message
Sen. Barack Obama, the presumptive Democratic nominee for president, is on vacation in Hawaii tonight. We believe. But, thanks to loyal Ticket reader Mark, just minutes ago we learned that the freshman senator's presidential campaign has confirmed that announcement of Obama's running mate choice is very near .
LA Times
I signed up. I think this is a very cool way to announce and they will get even more names for their base.