That's Caramelldansen, a 2001 dance single from Swedish group Caramell (it's generally played at double-time). It became part of a growing meme when two characters from the game Popotan were animated doing the aforementioned dance, which has now expanded-- you can find characters from almost any anime doing the Caramelldansen. The song was remixed a number of times for a new single that was released by the Swedes in Japan, now titled “Uu Uu Uaa Uaa,” which won single of the year (along with boyband Arashi's “truth” single).
Other anime-related winnings: Gake no Ue no Ponyo's title theme was among the best five songs of the year, and its soundtrack won Soundtrack Album of the Year, too. Oddly enough, though, BLEACH BEST TUNES was Animation Album of the Year. (Though Bleach does have a phenomenal soundtrack.)
I could list all the awards, because so many of the artists are ones
you'd be familiar with either because of their ubiquity (Ayumi
Hamasaki, Arashi, Utada Hikaru) and/or because of their anime themes
(Mr. Children, Namie Amuro). If I find an English-language list of
all the winners later I'll link it in the Daily Shin Buun. In the
meantime, the shot above is from the original Caramelldansen meme
(with Popotan), but
here's a little collection of other Caramelldansen shots, just 'cause
they're so cute.
god, is that enough of these for you yet? I'm getting cavities...