Yes, EU and US can play together

I noticed there was some confusion about this, so I figured I'd clear things up.

I've just managed to play together with a player from the United States. I'm from Europe (The Netherlands) myself.

So it seems like all western players use the same servers. No region locking.

Edit: Haven't seen a single Japanese player name, so I'm assuming we don't play with them. And I'm not sure about Australia, but I think they often use EU servers to begin with.