My personal pick for Obama vp seems to have very little in his schedule around the convention. He is confirmed on the short list. http://www.nytimes.com/2008/08/14/us/politics/14kaine.html?_r=1&ref=politics&oref=slogin

Tim Kaine: Governor of VA.

A more moderate democrat from a swing state that boarders another swing state. From my point of view, Virgina is the gate way to the south for democrats. If Obama can wrap up VA, he can concentrate more on other southern states like North Carolina (latest polls show McCain up 4). Kaine can also assure independent voters that Obama is not single mindedly to the left of them. Obama would also look a little more likely to work over party lines. This is definitly enough to get Kaine on the short list, but one or two more things would help...
He can speak fluent Spanish. What better way to connect the the Spanish speaking people in swing states like New Mexico, Colorado, and to an extent Florida.

Kaine does lack experence, but it would combine a govenors experence to a senators. And besides, it does not matter who Obama picks, the Republicans will still attack him for being unexperenced.
In the electoral map Kaine would help in VA (13 votes), his Spanish speaking would help in Colorado, New Mexico, and Florida. (41 votes) and Kaine would allow Obama to move people from VA to set up a ground game in North Carolina. (15 votes) Kaine could directly influence 54 electoral votes and indirectly influence 15 more. Total of 69 votes out of 270 needed. (That is good for a running mate) There is a slight chance that he could move more votes, but we will not go into that now.
Obama and Kaine seem to get along very well, they would be a good team in the Oval office.