from the faq:

Can I change Gateways like in StarCraft I to play with people in other regions?
Unlike StarCraft I, there is no gateway selection to allow you to play with players in other regions. You will only be able to play against players within the same region as you.

i want the gateway selection feature but i can't make a feature request because i'm not a beta tester. can someone make a feature request here:

http://forums.battle.net/board.html?sid=5010&forumId=25352532