How to do a footer gradient like sitepoint with GIMP?

I can do basic gradients in GIMP, but how would I do a gradient like this? The corners is the problem that I have. Any ideas?

You just got the job, haha.

I have been able to limp by with GIMP (no pun intended). I don’t really want to spring for photoshop for just that.

In Photoshop you can do that in 5 seconds with a large-sized drop shadow, but I’m not sure about GIMP, as I haven’t used that.