I've been advocating this for a while, but I wanted to get it out for a large-scale discussion.
Pros
Charismatic speaker
I listened to her speak once concerning the judicial nominees. This is the site, but I can't get the link to work. (http://www.cspan.org/congress/debate.asp ) Her speech was not only passionate and engaging, it was also logically straightforward and compelling. Therefore, I would argue that her speaking abilities combined with being an attractive woman would make her an awesome attack dog. Her credibility compared to Cheney is exciting.
Southern candidate in a winnable state
Kerry really needs help in the south. He has almost no credibility when speaking to southerners about southern issues. Mary has that in spades. Further, with a democratic Gov Mary's spot can be replaced by another dem.
Moderate Dem
A lot of left-leaning dems will not like much of her voting record. Nevertheless, we need a moderate to appeal to centrist swing voters. Bush is going to do everything he can to paint Kerry as a New England liberal. We need to balance the ticket; without a moderate pull we will not be able to pull moderate Republicans and right leaning dems into the fold.
"Military Mary."
http://landrieu.senate.gov/ What's better than a Vietnam war veteran at the top and a military Mary beside him?
Young
Though Mary is in her late 40's (its impolite to go into more details). She looks young. After 8 years as VP should be a strong candidate for President.
Pro Small Business
"her pro-growth, pro-business voting record has earned her the U.S. Chambers of Commerce's Spirit of Enterprise Award, and in 2002, the National Federation of Independent Businesses awarded her the "Guardian of the Small Business Award."" http://landrieu.senate.gov/ This background would definitely help Kerry in his economic message.
Minority Pull
Mary would have a strong pull with women voters and did well in reaching out to African American voters in her 2002 re-election campaign.
Strong, experienced campaigner
She already beat Bush in 2002, she can do it again. She's been in the political arean since she was 23. She'll have the contacts and skills. However, she does not come across as a typical, wonkish politician.
Media Attention
Any lack of name recognition would be easilty solved by the blitz that choosing a woman would have.
These have been my own musings and conclusions. I'm a bit tired of speculation about the same guys. Good or bad, we've all stated our opinions and analyses rather thoroughly, and have heard a plethera of speculation from various news sources. I would love to hear more in-depth speculation around candidates that haven't gotten a lot of attention.