At 42% poor ol' Joe is worse off than Al Gore, a man who bored people so much, they voted for George W. Bush instead. In fact, he can't even measure up to his predecessor Dick Cheney, a man who took polls very seriously indeed.
This is either "a fascinating and important" puzzle or, you know, perfectly understandable given Barack Obama Superstar is his boss and nobody really cares about a guy whose job currently consists of campaigning for candidates who don't need it, poking gentle ha-has at the eco-nazis who vote for his party, making reassuring noises in the Midwest, playing pessimist on Afghanistan, and visiting countries his boss would like to, but can't afford to, ignore.
He's so determined to the VP of Obama's dreams, he's even trained himself to be marginally polite to Cheney! That's some hard work, folks.
Also, since no report about Obama or Biden is complete without it, let us mention that Secretary of State Hillary Clinton is currently more popular than either Obama or Biden. This means she should have held both jobs.