I have tried the Lightwedge Paperback edition and would not recommend it. Certainly not for the Cybook (it does not fit the screen, which is important to get the light right) and not for pbooks (does not fit the page, to much fumbling when turning pages, to heavy, uneven light).
I use the
Mighty Bright which is very good (tip: attach it to the bottom of the device for better balance)