Professor Layton’s "hint" in last week’s issue of Famitsu was about Professor Layton vs. Ace Attorney’s release date. The magazine confirmed Professor Layton vs. Ace Attorney will be released on November 29 in Japan. Level-5 is developing and publishing the title in Japan.
I think Siliconera is one of the few (maybe the only!) English site that played the game so far. Read our impressions of Professor Layton vs. Ace Attorney here.