McCain Pre-Announces The Announcement

What's the wisdom in John McCain's pre-announcing, to conservative-friendly media, the date (August 29) and location (Dayton, Ohio) of your vice presidential announcement? 

This week, it splices into the threads of attention that Barack Obama's campaign is sewing ahead of Obama's announcement.

Next week, it ensures that the press pays at least mild attention to McCain.

And most importantly: it helps McCain artificially build a crowd of 10,000 people or more in Dayton, Ohio and the other locales he's taking his VP on tour.

Note that McCain's convention acceptance speech is that next Thursday, on the same night as the NFL season opener.