According to MacRumors, one of the readers emailed Steve Jobs if Apple was ever going to enable Airplay to stream videos from third party apps and Safari Pages. Surprisingly, Steve Jobs replied back!
Q: Hi, I recently updated both my iPhone 4 and iPad to 4.2. I think my favourite feature is airplay. This is seriously amazing and makes sharing content seamless. I just purchased Apple TV and was wondering are you ever going to make airplay video work for videos in safari and 3rd party apps? I hope to get a response. :)Airplay is the technology introduced in iOS 42 that lets users stream content from their iOS devices with iOS 4.2.1 to an Apple TV. Currently, Airplay can only be functional on Youtube, photos, and video apps that were part of the iOS but it has been extended to all apps thanks to AirVideoEnabler. It is assumed that Steve will be improving upon AirPlay in the new future.
A: Yep, hope to add these features to Airplay in 2011.
Even though Airplay doesn't support third party apps, jailbroken device can stream content to other iOS devices or from iTunes if they are on the same network.