A Vice President typically fulfills one of three important roles in the campaign. First, they can be the campaign's attack-dog, giving a high profile to attacks the candidate cannot utter himself. Second, they can deliver a critical state or group. Finally, they can confer credentials in a particular area.
While it's no secret that Joe Biden, that wonderful curmudgeon, has always been my favorite pick for attack-dog VP. For Obama, however, there is a powerful choice who is signaling his availability.
Colin Powell will further solidify Obama's transpartisan appeal, and he is military-experience personified. That checks boxes 2 and 3 nicely. With Powell, who has signalled that he is strongly considering supporting Obama, we can turn this into the landslide we all want to see.
This will require explanation of the lie-filled UN presentation, of course. Distancing himself from Bush is a must. But Powell could easily say that certain discussions are still covered by executive privilege, but that a Truth and Reconciliation Commission would be a good idea.
Despite the slight danger in further pissing off the Left, this is a clear winner. Do it, Obama!