I actually see Governor Susana Martinez of New Mexico as a possible VP candidate this year for Romney. Though she's really inexperienced (moreso than even Palin), she provides two things he lacks; Latino support and Tea Party credentials. Martinez won't last as a Governor past 2014 anyway, so it could be an advantageous pick if Romney wants to seem "multicultural".
Maybe if Santorum or a convention dark horse gets the nomination, but definitely not Romney. The very last thing he needs on a ticket with him is another governor to remind the voters he was the Governor of Massachusetts and Romneycare.