Yes. It's about Windows Mobile registry, so it has to be for Windows Mobile.
Since I'm using an SD Android ROM to which I can boot for testing purposes (Windows Mobile is still better IMO - because it's more complete, more versatile and allows easier user-level tweaking, plus it's not Google's slave), I noticed the picture quality is optimum already under Android. At least using (old already) the build I'm using.
But the regsitry trick is clearly efficient, as I could compare with another HD2 that's not been tweaked.