What a difference a day makes.Gov. Kathleen Sebelius spoke to the Democratic National Convention on Tuesday, and vice presidential nominee U.S. Sen. Joe Biden, D-Del., speaks Wednesday night.So now that it has been a few days since Democratic presidential hopeful Barack Obama picked Biden – and not Sebelius, who many thought was a top contender – the question becomes why?Some have theorized that Obama realized the public was worried about his lack of foreign policy experience, so he picked the veteran senator. Others say Sebelius wouldn’t have done much for the ticket in gathering electoral votes. And some have figured that because Obama didn’t pick U.S. Sen. Hillary Clinton, D-N.Y., he couldn’t select another woman without angering Clinton supporters. What’s your take?