It's a well known technique. Poor mans soft focus. Lots of people use it, or want to but forget about it because it's so simple (the best stuff usually is). Some people also use a clear filter on their lens and smear petroleum jelly (Vaseline) on it. Its gives you a different effect and you can shape it so that it isn't smooth all across the picture or leaving patches clear if you want to. Just make sure you don't get any on your lens. You can also use a pair of tights stretched over the lens to give you a similar soft effect. I don't know if it'll work, but different colours may act like a very gentle colour filter at the same time.