Level-5 has trademarked Professor Layton and the Last Specter in North America, suggesting that the forth instalment in the series will see a Western release after all.
Professor Layton and the Specter's Flute was the last game to be released in the series on DS in Japan, and was subsequently followed up by Professor Layton and the Mask of Miracle on 3DS for its launch. Neither have been released outside of Japan.
Fears were mounting that Nintendo might overlook the fourth title when localising the games for America, Europe and Australia in favour of pushing the 3DS, despite leaving a gaping hole in the storyline.
However, it looks as if the DS has some life in it yet and that both Layton 4 and 5 will be released in English-speaking regions. Now we just need to try and work out what it will actually be called in Australia, as we've historically had a different title to the US.