Saw this at babbages.com also.
From what I can tell it requires no soldering whatsoever. The only thing you do is pop out the screen from the GBA. Then attatch the light screen over where the plastic screen used to be and you're done. The light screen is attatched to a plastic part that draws power from port on top like all the other GBA peripherals.
It's not an official Nintendo product and I think it's made by Innovation, the same ppl who did the TV thing.
I might buy another GBA and this. It's the same price and way easier to install. I hope it's just as good.