Well I gave it a shot on a blind whim and had to patch. After I downloaded patch 1.02 I actually did get into the game and there are around 500-600 people in the game right now.
And I have a US account and a friend also managed to log in as well. (And started up a private passworded game just for kicks)
If you're getting login failure make sure you're using your Game ID and the numeric password you signed up at Konami with.