I haven't seen this posted anywhere--just thought I'd say how cool I think the effect looks when the sleep button is pressed. I love that retro CRT-like flash off!
Probably because it isn't a RAZR feature. Someone can correct me if I am wrong, but I believe it was a feature introduced with Gingerbread.
I figured it wasn't exclusive to Moto, but I can tell you it didn't show up when my HTC Droid Incredible was upgraded to Gingerbread.