Apple has one or more pending patents for it's (rather trivial) live streaming protocol and so far only agrees to RAND terms, see https://datatracker.ietf.org/ipr/1142/ I have not seen a confirmation from Apple that it will offer royalty-free licenses if the protocol becomes a IETF standard. That should imho be a requirement for HTML5 adoption.
Also it may be better to adopt another streaming protocol for HTML5 because the Apple's protocol is not suitable for low latency streaming.
However, Apple has a method of doing this with entirely standard HTTP and a few metadata files, as this is how you do adaptive bitrate content on the iphone: http://developer.apple.com/iphone/library/documentation/Netw...
The formats and methods Apple provides in the spec for the IPhone can be used for both Live Content and for adaptive bit-rate pre-recorded content.
I hope eventually the iphone http streaming spec or a derivative would get adopted into HTML5 :)