Apple Adds "Apple Events" To Apple TV, Will Livestream Today's Event

MacRumors:

Several MacRumors readers have noted that Apple has added a new “Apple Events” icon to the Apple TV, with the company revealing that it will be streaming today’s media event live.

I’d love to know what factors are involved in deciding whether an event gets streamed or not. Is it based on popularity of the product? Location? Whether Apple wants to more succinctly send out a certain message?

Are these intermittent occurrences test runs, so that the goal is to eventually stream every event?