Will iOS automatically update to iOS6 without going to Software Update?

I have some friends who have an iPhone but don't go to websites like MacRumors and therefore do not know iOS6 is out. Since I know it's out, I just go to software update.

I would like my friends to be updated to iOS6 at some point. I was wondering if I had to make them aware of the update or not. If I never tell them about it, and they never go to Software Update, will they ever know an update is out? Or do I have to make them aware of it and tell them to go to Software Update?

Okay. But let's say it's been a month since the update has been out? Will the user receive some sort of popup at some point?

I have to believe that most users who are not on top of Apple's software releases do not routinely go to "General" in settings and select software update.