I quite like the idea. Personally, i have never clicked on sponsored results. Simply because they look useless almost everytime. But may be with this, people will click on sponsored searches a bit more. Then their is acceptability. Google search is just better. So i dont know how good their search algorithm is and a charitable cause alone will not drive their primary business. Still like the idea.

Edit: sorry just saw its powered by bing. Not a fan but my latter point is not relevant.