Opera has their own server infrastructure for Opera Mini, although I'm sure it could run on EC2 as well. For a while all the servers were in Oslo, Norway, but now they have servers around the world. Here's an article from last year where they installed some new servers in Iceland: http://my.opera.com/portalnews/blog/2010/11/01/20-million-op...
Perhaps Opera Mini runs on Amazon EC2, which would mean they use the same infrastructure ;)