Donklephant asks the same question and posits an idea which I have previously mulled.
Governor Schweitzer is a very popular Democratic governor in an otherwise very red state (Montana) and, as Justin notes, he's pragmatic and can walk the bipartisan walk like he talks it. While it can be said that he'll just be the VP were he Senator Obama's choice as running mate, I think Governor Schweitzer would provide valuable advice to candidate and President Obama.
As for this talk of Senator Webb, I'm not sure I'm comfortable with him just on the basis of having two legislators on the ticket. I'd rather have one person with legislative experience and one person with executive experience (see Clinton/Gore) as a ticket. It provides a balance on the ticket that goes beyond simple demographic balance, but also reflects a balance in leadership positions.
Those are my thoughts.