I just seem to recall Dimbleby saying something about Florida's value being representative of Puerto Rico's population, even though they don't have the right to vote in Presidential elections, or something like that...
I may have imagined this. I am not sure.
Looking at the island's population, I would expect it to receive it approximately seven Electoral College votes. This may be taken from other states, or may be generated as new votes. I would expect an even number to remain the overall total though, so perhaps one state could lose one point to Puerto Rico and then it gain an additional six, for a total of 544? Alternatively, other states could lose votes (perhaps CA and TX two and FL, NY and IL one)?