Well, Barack Obama has gone ahead and picked someone other than Hillary Clinton. I can understand why Obama would be looking to go in another direction. Given Hillary's popularity, committed base, and probable importance in the upcoming electoral contest, her clout could make her something of a co-president.
Unfortunately, in declining to name Hillary, Obama has created an opening which McCain quickly seized. It remains to be seen exactly who Sarah Palin is, and I do not think that there mere fact of her gender will necessarily sway that half of the electorate. Particularly since Republicans tend to be on the unpopular side of many women's issues.
Nobody can fault Obama for wanting to preserve his independence from the kind of entanglement a Hillary VP would necessarily bring. Now we can only hope that he, and we, don't live to regret it.