Patrick Ruffini has the idea of the day for McCain:

The premise is that the campaign would release the name of the VP nominee one hour in advance to 100 supporters selected at random from those who signed up for McCain e-mail list as a result of this campaign. This truly would have been "hearing it first" because no more than a few dozen ordinary people would actually "hear it first."

An hour later, the announcement would be webcast on JohnMcCain.com, with a big fat e-mail signup field and donate button next to the video.

As Ruffini notes, this is similar to what the Obama campaign has said it will do.