I use it in the computer lab with 1st grade and up. We create posters that go along with content being taught in the classroom. The older students get more time to explore and create on their own.
Great website where kids can make their own animated movies. Kids will probably need an adult to help them figure out how it works at first, but once they get going there's lots of room for creativity, as well as logical panning (laying out activities on a multi-track time line). Can share videos. We haven't gotten any hits yet, so no opinion re: appropriateness. Earn coins when you make movies -- seems like a good incentive system. Has a point, unlike Club Penguin were you earn points by playing silly games.