In a post at the Cave development blog today, development head Makoto Asada revealed that he's making a shooting game for Windows Phone 7. Development on the game is currently 20 to 30% complete.
Asada did not sure specifics about the game, only saying that it's an original title. He promised to share screenshots once they're ready to be shown.
Because everyone knows Windows Phone 7 is the platform for bullet hell shoot 'em ups.