I'm sorry to do this, but I'm here to dash your dreams of playing Monster Hunter 3 Ultimate with friends around the world. It's been confirmed that online play for MH3U is going to be local to your country. No Europe to North America, or either to Japan. Capcom's Yuri L. Araujo commented on the issue.
I'm not thrilled with the servers being split either... I am definitely aware of the demand and feedback, not only in this thread, but also from threads before finding out these bad news; so be sure that I will pass it along. There is no guarantee this will change though. =/