The long awaited cross-over game between Professor Layton and Phoenix Wright will be released in Japan on November 29th. The game will also have a playable demo during the Tokyo Game Show coming up soon.
The game will take place in a fantasy setting called Labyrinth City where our professor and defense attorney will help some wrongly accused individuals. The gameplay will be split into two different parts, an Adventure Part where you play as Professor Layton and do what he does best, solve puzzles and gathering clues. The Trial Part is where you take control of Phoenix Wright in a special courtroom to go through a "Witch Trial" where there will be multiple witnesses taking the stand at the same time.
There's currently no news as to whether the game will come stateside, but with the recent announcement of Ace Attorney 5 getting a western release, and with the extreme popularity of both Professor Layton and Ace Attorney games here we should expect them to bring it over sometime in the future. Looking forward to it when it does, even though I've never played a Professor Layton game.