Professor Layton and the Mask of Miracle in Japan, is no exception. It arrived in the land of the Rising Sun last February, and hasn't been released in Europe or North America yet. But it looks like one of those releases is planned: The end of a trailer for Professor Layton and the Spectre's Call in Europe teases that players should "get ready for an all-new Layton next year."
Presumably, that's the 3DS title (though the name usually changes on the trip over), and that tease means we'll see it out sometime in 2012. We haven't seen quite as much confirmation on a North American release, but since the last title hit Europe this week and North America last month, 2012 is a good bet for us 'mericans as well. After all, it's not like Level-5 doesn't want to release it here, it's just that translation can take time.