Sources close to MacStories have informed them that Apple is preparing a major update to iOS i.e. iOS 4.3 sometime in December this year. This new update will allow you to subscribe to content like the much talked about News Corp’s iPad-only newspaper, The Daily.
This rumor coincides with another rumor according to which Apple will be holding a special media event on December 9 to announce this new subscription based content feature. John Gruber of Daring Fireball noted:

[This] initiative is going to launch with a press event, with Murdoch (and perhaps other newspaper and magazine executives) joining Steve Jobs on stage …
The date I’ve heard is December 9, but that’s a Thursday, which would be somewhat unusual for an Apple press event. My guess is that they’re telling people December 9 but it might slip back to Tuesday or Wednesday the week after.

MacStories however has warned that Apple might delay iOS 4.3 because of the recently launched iOS 4.2.1, which was delayed for about three weeks from original release date due to last minute WiFi issues found in iOS 4.2.x for iPad.
Like any other rumor, take this one with a grain of salt. I personally don’t think Apple will release a major new update only two weeks after iOS 4.2.x has been released, which is also major update that ports many iPhone features to iPad, along with AirPlay and AirPrint.