Hmm...
... Rihanna's "Umbrella" was big!!... ... but Nelly Furtado's "Say it right" was bigger and broke records in many european countries... so... I would say "Say it right" is the song of the year, at least here in Europe!!...
(Example: "Say it right" is at number 1 on Czech singles charts for 23 weeks!!!!!! "Umbrella" reached number 2 about weeks ago and is about to descend now that "Big girls don't cry" is about to take the charts by storm...)