The New York Daily News reports that 46,000 snowbirds are registered in both New York and Florida, and that several hundred of said voters have voted in both elections.
"Of the 46,000 registered in both states, 68% are Democrats, 12% are Republicans and 16% didn't claim a party."
As this inaccuracy in elections might seems to be leaning toward the Democrats, it is unlikely to add to the claims that Bush stole the elections (unfortunately, both parties pull every underhanded trick in the book to steal elections).
With an increasingly mobile society, I suspect between state votes will just continue to increase. I know I tend to move between states regularly.