This is a fine, angry rant about the Jonas Brothers, which I found on the kottke blog.
The South Park bits are spot on (and surprisingly profane -- I guess I haven't watched in a while.) I had not before heard of Purity Rings, and was only a little aware of the Jonas Bros as a preteen phenomenon. I never thought of the sexual impact of Disney too much, beyond noticing that the female heroines like the Little Mermaid manage to combine neotony with a somewhat inappropriate voluptuousness.