People are using this:
http://www.deviantart.com/deviation/1872584/
Oddly enough, I found this by typing “layer styles gimp” into Google. Go and figure.
Also, for people talking about Googles SOC projects, they are also doing this:
http://www.gnome.org/bounties/Google.html
Notice the two on the bottom of the list.
frankly, i can’t use the gimp. i’ve tried and tried to get used to it, but it kills me every time. and the brush system is damn near unusable, for me at least. but hell, after what i’ve seen come from some of these other blenderheads, go ahead and give it a shot.
It’s way better now than 2.2.x. The improvements since the 2.3.x branch started coming out are huge. And it’s getting better all the time. If you care, there are a couple of good threads concerning the improved brush system in Gimp here at BlenderArtist.