Sounds to me as though Romney is trying by association to tap the power of Palin influence?
Say what you will about Mittens he didn’t get to the level of success in business and politics without recognizing trends. He can not win without the base and Palin is a large part of the base and her opinion/endorsement help push conservative candidates over the top.
Palin is stacking Congress with an A team of strong conservative leaders who will be shaping future policy and righting the nation’s drifting financial ship for years to come. When the time comes favors mean a lot in DC.
Whether Sarah gets a speaking slot at the Convention or not, she will eventually come out for Romney. To not do so would hurt her to badly politically. She could still be the nominee in 2016.