Remember last week when we showed you a Cydia App that enabled Airplay for all devices? Based on the ease of getting it to work at the time we said:
This is big because it means Apple could easily (and will likely) enable [Airplay for all apps] in future versions of the iOS.
Today Steve Jobs went on record (more or less) saying that indeed Apple is planning to build it into Safari and the SDK.
Until then, there are the hacks.