Congratulations to Nina Agdal for winning Rookie of the Year. Looks like it was a nice tight race, with a percentage point separating all five girls.
Kate Upton gets referenced a lot as the 2011 Rookie of the Year, but I don't think there was ever any official selection. If I remember, the guy who writes Extra Mustard mentioned in passing that Kate was his ROY, and it kind of stuck.
(Not that there would have been any doubt about Kate.)