The Arena.Net blog has been updated with new information for participants in this weekend's first beta event. Information includes both the EU and NA server lists and requirements for transfer to servers outside of a player's purchase zone.
When you log in to the game for the first time, you will have the opportunity to pick any available server, or home world. If you choose to select a home world that is in a different region from where you purchased your game, you will be logged out for a short period of time while your account is moved to your new region. Once you have selected a home world, all the characters you create will play on this world and will represent it in our world-versus-world (WvW) format.