After some fiddling, I found some gotchas. Most importantly, SSH keys, security groups, and AMIs are not replicated between regions. You can use the ec2-migrate-bundle command (from the AMI tools) to copy your images from the US to Europe.
Its acctully hosted in Ireland (likely Dublin), as confirmed by Amazon. Kind of a shame, its about as west as you can get in Europe! Those in England will get pings of around 100ms, and god knows what those in western europe like Italy, Greece, etc. will get...