site_bg.jpg is 1992px wide,
footer_bg.jpg 9s 1500px wide.
That might be the empty space that you see at the right end.
You could use a css3 background-image property, but it is not widely supported, yet.
Or you could just center and repeat (x and y) the footer background image:
layout.css, Line 175
background: url(../images/footer_bg.jpg) repeat 50% 0;
That leaves the inline containers with links in the footer left-aligned and your copyright and site link stacking to the right, also.
Looks like those two categories of containers need to be centered somehow.
Let us know if you need help doing that (I'm shirking working with the grid).