Barack Obama's endorsement by the Grateful Dead showed the extent to which he is bringing voters out of the woodwork. Typically in campaigns, you start with 1/3 supporting your side, 1/3 supporting the other side, and 1/3 ready to be convinced. The middle is the battleground (unless you buy into the DLC playbook of pissing off the base to try and win over the other side's base, which is why no Clinton has won 50% nationwide). The other option is to not buy into the voter pool as a zero net sum game and bring in new people. To date, Barack Obama has excelled at expanding the pool and bringing in young voters and first time voters and boosting turnout.
When it comes to the Grateful Dead, it is almost a joke when it comes to getting Deadheads to care about politics. It might be the least friendly demographic for increasing participation in electoral politics. The Dead didn't step up against Nixon or any other major threat to America since. But they have been inspired by Barack Obama to come together for a reunion concert to Get Out The Vote. I'm proud to be there and will be updating below the fold, you can listen to a Live stream here (beginning at 7:30 pacific + Dead time).
Talk about contrast. Hillary's event was a huge pain to get media credentials. Top down, the was seating for less than 100 stanch supporters as part of a simulcast in dozens of cities with her endorsers. Meanwhile, Obama's grassroots campaign inspired the Dead to get back together and they sold out the Warfield for Obama in less than twenty minutes.
It is now 45 minutes past the start and hundreds are still waiting in line while the bar is stacked five deep.