I've made my first attempt at body blushing a ball-jointed doll, and I'm hooked. My guinea pig was Whisper, a resin BJD by Goodreau, 17" tall. Here are some safe results, which I've uploaded to Flickr.
The technique is super-easy--I'm (really) no artist. All it takes is some soft chalk pastels, some acrylic spray primer (I used All Purpose DullCote by Testors), Magic Eraser to clean the doll before I got started, and some brushes--an angled one, a tiny one, and a large round soft one for blending.
I have, of course, uploaded all the results to Mobile Me and also to Flickr, if you'd like to see the rest of the photos. But don't look at those if you're offended by photos of nude dolls. I have some before/after photos of what nude Goodreau bodies look like without body blushing as well.
I really like how the shadow adds more life to the doll, especially on her collarbone. I will definitely be doing more of my dolls like this. It's so much fun!