Heavy Rain was a pretty decent hit when it came out, and it's nice to see it getting Move support. Particularly since it makes sense, the entire game was played shaking a controller all over the place after all. Why not shake a wand instead?
Sony has released a nice round of screenshots on their blog, showing how some of the motions will convert over and what the new icons will look like. If anything it could be more receptive than the Dualshock, particularly for the 'up and down' motions. Having reviewed the game personally, I know those tended to be hit or miss actions. Anything that makes the gameplay smoother (and justifies purchasing a Move) is a win in my book.
The update will be a free download from PSN for those who have a copy of the game, and if not a Heavy Rain Move Edition will be released sometime during the holiday season.
Source: Playstation Blog