I've been shooting almost exclusively with my iPhone4 for almost a month now. The IOS 4.1 update's new HDR photo mode is pretty fracking amazing. Here's a quick test shot I took in my extremely interesting living room. Hand held, in low light. The first/top shot is "normal" exposure, the one that the iPhone would have picked for a regular shot without the flash. The second/middle image is HDR tonemapped. The third/bottom is the HDR version, pumped through Aperture to apply my usual tweaks (adding some contrast back, setting white balance, vignetting, etc...)
The lamp in the "normal" (top) version is blown out, without any details in the lampshade. The HDR version (untouched in the middle photo, and adjusted in the bottom) looks pretty close to what my eyes see. No chrome halo effects in the iPhone4 HDR. Just pulling details out of blown out or underexposed areas.