Found in a Famitsu Magazine article, there is a small section for Monster Hunter 3 G which showcases the Slide Pad attachment for the Nintendo DS. Written as 拡張スライドパッド / Kakuchou Slide Pad or "Slide Pad Expansion", the attachment gives it an additional pad on the right side and makes it that much more clunky to carry around and use. However, it is said that the Slide Pad is simple to install; it's as easy as mounting the 3DS onto the Slide Pad, holding it in place on the hinges in the back. It is long overdue to add this second pad, but better late than never... if it's cheap.

There is no mention of the cost or release date for this thing, but after the 3DS price cut, this (hopefully optional) accessory might be a factor in bumping the prices back up there.