Apple officially rolled out its new plan for content subscriptions in the iPad. What it boils down to is that if you purchase an iPad version of a newspaper or magazine, Apple gets a 30% cut. If you buy more issues while on the iPad or if you choose to subscribe within the app, Apple gets a 30% cut. Content providers can offer their own subscriptions and Apple gets nothing off those BUT there can be no external links within the iPad version to, say, a browser where you can buy it on your own. Also, the iPad subscription price needs to be the same or lower than the outside price.
The real dust-up here is not the magazines, however, its services like Netflix or Kindle or Spotify or Hulu Plus. Suddenly, they're faced with either making a lot less money, losing money, or jacking up their rates to accommodate Apple's demands. It doesn't take much detective work to realize that Apple has its own competitors to all these services.