Just found this. Apple will be streaming live video of the event via Safari and Apple TV.
Watch a live video stream of the special event online or via Apple TV starting at 10:00 a.m. PDT.
Live streaming video requires Safari 4 or later on Mac OS X v10.6 or later; Safari on iOS 4.2 or later. Streaming via Apple TV requires second- or third-generation Apple TV with software 5.0.2 or later.