Here's my take...
That is a terrific idea! There have been many a time on the bus or otherwise on-the-go where I wanted a solid place to use a mouse whether to fix up a piece of CAD in Inventor or fix up a Covenant invasion in Halo and other games. (I resorted to my pointing stick, although it wasn't great.)
If its stable enough and doesn't smash the laptop's plastic housing (maybe with support running over and along the underside of the computer) I think it can be a marketable product.
Also, I think Qi-enabled AAA batteries could actually go somewhere.
I kinda wanted Qi in my laptop palmrest or a Qi-enabled slide-out flexible bay accessory. (although I realize putting it in the palmrest interferes with use.)
Maybe you can look into making a similar mousepad that slides into the flexible bay of some laptops. (replacing the CD drive or battery...) Although I think that feature going the way of the dodo in mainstream computers.
I honestly am excited to see where this goes. I don't have as much as a use for it nowadays but I think there's a market.