Keen-eye Chris Kohler of the Gamelife blog notes that, in the final retail build sent out to reviewers late last week, it's mentioned in the instruction manual that there will be some sort of link from Curious Village to a future sequel.
According to the manual:
"There's even a surprise feature that involves the sequel to Professor Layton and the Curious Village!"
Professor Layton is already in three volumes in Japan. The follow-up to Curious Village in Japan is Professor Layton and the Devil's Box, and this mention in the Curious Village manual all but confirms the next game is on the way in the US.
Bone up for part two, folks.