Developer Blizzard today released a full list of the region servers that will be available in Diablo III, again reiterating that you'll be able to play on any region's server in the upcoming action-roleplaying game.
Game servers will be divided into three regions: The Americas, Europe and Asia. Any player will be able to pick any server to use, although you won't be able to transfer characters or items from server to server. You can switch between servers as many times as you'd like.
Here's a full breakdown of the server regions:
The Americas - For players in the US, Canada, Latin America, Australia, New Zealand, and Southeast Asia. Europe - For players in the European Union, Eastern Europe, Russia, Africa, and Middle Eastern countries such as Israel and the United Arab Emirates. Asia - For players in South Korea and the regions of Taiwan, Hong Kong, and Macau.
Auction houses, stashes, friends lists and most other individual info will be region-specific and won't transfer when you switch regions.
Blizzard's last game, StarCraft II, placed a strict region-lock on many of its servers. To play on multiple region's servers in most cases, you'd have to buy multiple copies of the game.
Diablo III Global Play FAQ [Blizzard]