I don't know enough to get involved in the Veep-stakes game, but Steve Clemons does. Yesterday he published his opinion that it will be Joe Biden, and offered his logic.
So far nothing else I have seen makes as much sense, but this game is a lot like arguing for "Intelligent Design" (Creationism) as a scientific theory of the development of Species rather than Evolution. Evolution takes known and verifiable facts and builds a theory to explain how they could be used to explain the evolution of Species.
"Intelligent Design" sets up a process in which every logical barrier to human understanding of the development of species is turned over to a supernatural Intelligent being to explain because God can perform miracles. Instead of being science, Intelligent Design assumes that human beings cannot understand the reason or mechanism for the development of species. Science is a dead end because only God - the Intelligent Miracle Worker - can possibly understand that. That's the definition of a miracle. Something occurred that has no known cause and was directed by a miracle worker no human can ever understand. So logic and science are useless in understanding how something occurred.
Steve's analysis is somewhat similar to Intelligent Design, in that he is attempting to apply logic and fact collection to an event that ultimately will be decided by a single intelligent decider - in this case, Barack Obama. The only difference is that we know the mechanism, so the decision will not be a miracle.
Of all the guesses about the Veep decision I have seen, so far Steve's is the best I have seen. But if I have gotten over my skepticism of any and all current analysis of the current writings on who the Veep will be, then my job here is done.