There is only ONE gun accessory worth considering: Playstation sharpshooter.
Will release on Feb 22, along with Killzone 3.
The sharpshooter is developed with Killzone 3 and SOCOM 4 (April) in mind. I
expect all future move-FPS will support sharpshooter in some way.
Don't know about COD7. Currently only FPS games supports move are MAG and
Killzone 3 (public beta as we speak)