I walked past the kids pledging allegiance to Tesco most days when I was in Islington:

http://images.google.com/images?q=banksy%20tesco&um=1...

Edit: For people outside of England, Tesco is one of the bigger or biggest convenience store chains, similar to 7-11. The kids are wearing traditional school uniforms. So it'd be similar to graffiti of American kids in conservative, traditional dress saluting the 7-11 logo.

It was released in London in March so is no longer on in most cinemas. That said, the Prince Charles in Soho is showing it on Monday and Wednesday lunchtime: http://bit.ly/9AqEZ7

I know it's too late now and the run has finished, but Curzon were playing it in their London cinemas last month/start of this month.