Rubio isn't Romney's VP yet though and something tells me he woon't for a few key reasons. Also, if Rubio was a VP, he wouldn't exactly have time to plug in the rubio da, he'd be nonstop on the road most days stumping for Romney. But anyway most likely Rubio won't be VP for a few reasons

1. He doesn't exactly excite most of the Latino base, most Latinos seem to be regarding him like most other republicans, and his cuban-american heritage doesn't exactly inspire the sense that he has much compassion towards other segments of the latino populace.
2. He has way too many mini scandals and oddities the Dems could seize on. The random state funds he used on himself, the fact he was a mormon as a child, the fact his grandfather was also an undocumented immigrant, his at times slickiness, etc,etc
3. Romney doesn't really connect with him personally. Romney likes to go for safe choices he's comfortable with, meaning it's likely Ryan, Portman, or some other figure is far more likely then Rubio.
4. Picking Rubio now would be too predictable and would seem even a bit boring now.

Also, as I've said before, the GOP is almost never united on immigration, that's one of their key fault lines.