As discussed in The Nation, Senator Obama has narrowed his choice down to who he wants as his running mate. John Nichols puts it rather well:

Obama needs a running-mate with foreign-policy "stature." That’s not a
governor, and it’s probably not Bayh — whose record of accomplishment
in the Senate can best be summed up as "Democrat from Indiana."

So that leaves Biden, the chairman of the Senate Foreign Relations
Committee, and Clinton, whose international credentials are actually a
good deal more solid than even her advocates recognize.

Senator Biden would trump any potential candidate on foreign policy, including Senator McCain and his eventual choice in the number two spot. The VP debate would be a sight to see as Senator Biden is known for his verbosity, which would be a factor, but also his quick wit and vast experience. He can play every role necessary moving forward and while perhaps not infallible, certainly a strong and steady hand who knows his way around Washington.

It’s quite possible that Senator Obama is also considering someone who could really help navigate legislation and govern in a post-election victory. Governor Kaine or Senator Bayh can manage in their own states, certainly, but a veteran Senator with any number of chairmanships and friends on both sides of the aisle would be a whole new level that could be the most productive first hundred days in history. Senator Biden as the Vice President would create the most balanced (and potent) ticket possible, minus former Vice President Gore whom is also being whispered.

Obama/Biden is a winning combination for the party, and more importantly, for the country.