Ask HN: Any advice on legal agreements for user data hosted across the Atlantic?

I'm working on a project that will require me to be able to host UK (and possibly other countries) user data in the U.S. I'm not ready to do launch announcements yet but I was wondering if people had advice on how this works.

I want to go talk to my lawyer armed with some idea of what to expect. I know there is the Safe Harbor agreement which helps with the UK Data protection act, but is there anything else that I should know about? Do people have advice on getting this kind of thing sorted out?