Here is a civilised response - I don't know what you're talking about since my 2011 13" does not have the issue that you describe and my screen back-light is certainly not leaking at the bottom. (see screenshot below)
In your screenshot, are you talking about the lit-up area around "Macbook Air"? Are you sure that's not a reflection of your keyboard back lighting?
[url=http://i52.photobucket.com/albums/g35/da_seb/th_photo-4.jpg]Image[/URL]
There's a gradient effect at the bottom of the screen in the original picture.
Hard to say anything about your own screenshot, because you haven't extended the browser window to fit the screen (or any white background). Now since the dock is in the way, it's hard to tell.