Unfortunately players in different regions will not be able to interact with each other in any way. This includes:
- Playing games together
- Viewing profiles
- Adding them to friends list
- Any form of in game chat.
Currently (the end of Season 1) - the only option you have is to start a new account in the same region as your friend.
There is no way to transfer your account from one region to another. This may change in the futurefuture†**, however I'd imagine that it would incur a charge in the form of Riot Points.
If you decide to create a new account, bare in mind that playing in the wrong region could also give you in game latency issues, which will have a negative impact on your gaming experience, depending on the level of the problem.
**† http://www.leagueoflegends.com/board/showthread.php?t=165067&page=7
Jesse Perring
Customer Support Specialist
09-13-2010, 11:40 AM All of the feedback is always greatly appreciated. We are definitely paying attention. Unfortunately, right now it's just not possible from a technical standpoint to transfer any account content, between two servers, or even on one server. It's something we're thinking about for the future, but we can't be sure if or when it will be available yet.