Oh, this is delicious...
According to FairVote.org, Jenneifer Sheehan, Legal Counsel for the RNC, plainly stated in a 2008 letter to Nancy Lord, Utah National Committeewoman, several weeks before the convention,
“The RNC does not recognize a state's binding of national delegates, but considers each delegate a 'free agent' who can vote for whoever they choose.
The national convention allows delegates to vote for the individual of their choice, regardless of whether the person's name is officially placed into the nomination or not.” (Source)
This means, much to Romney's dismay, of all the delegates that finally make it to Tampa, just as it was determined to be the case for one of his '08 delegates, are all allowed to vote for anyone they choose, even if that happens to be Rick Santorum, for instance.
The twist to the story however is that the vast majority of the delegates emerging from the states thus far, that aren't Romney's, have actually stated to be voting for Ron Paul.
Time to cue the music...