It seems there's a sequel to that Miles Edgeworth DS game but there's no plans to release it outside of Japan. Kind of sad, I guess they want to focus on the 3DS instead. Hopefully they'll still release other games in the series in the west, so far there hasn't been any confirmation about that Phoenix Wright/Professor Layton crossover. I couldn't find another thread on this so I don't think it was posted here before.

http://en.wikipedia.org/wiki/Gyakuten_Kenji_2