Only just seen this interview (posted on LogoDesignLove) from back on the 20th of November, from the New York Times, Steven Sender interviewed Sol Sender, designer of Barack Obama's campaign logo, I found it an interesting read so thought it would be worth sharing the link 
The ‘O’ in Obama - Campaign Stops Blog - NYTimes.com
The ‘O’ in Obama - Campaign Stops Blog - NYTimes.com

We actually presented seven or eight options in the first round, and the one that was ultimately chosen was among these. In terms of our internal process, though, I believe the logo — as we now know it — came out of a second round of design explorations. At any rate, it happened quite quickly, all things considered. The entire undertaking took less than two weeks.