The affordances for swiping through Springboard seem to work pretty well. More important than the dots is the physicality of the animation. You can wiggle the current screen back and forth with a small motion and transition with a more dramatic one, but either way there's a clear directness to the interaction.
All swiping should work that way, and Apple is emphasizing the importance of "physical" dynamics in iOS 7.
That's a great point - I think it does make it a lot better when there's some kind of connection between a physical movement and the response from the app. The worst kind of swiping gestures are the ones where you have to get it just right, and then a menu "magically" appears out of nowhere.
I think another possible way of indicating the presence of a gesture might be through clever use of shading - for example, a subtle gradient on the edge of the screen where you can swipe, giving you the impression that there's something "just off the screen". I haven't actually seen this in an app yet - not sure why this isn't done more, especially for the Pull To Refresh trick.
All swiping should work that way, and Apple is emphasizing the importance of "physical" dynamics in iOS 7.