Well, did Windows Media use the same port as Real? Apple strength is its media authoring base. If anyone can simply hook a FireWire based DV camcorder to a G3 and stream it away, it will do.
There will be millions of FireWire based camcorder owner in a few year (now seem to limit to the high end model).
They gives free streaming server. Soon someone will have binary ready for all platform (or already?).
Now streaming live media limit to those with the card that work with the particular vendors. On the other hand, Apple Quicktime 4, FireWire and low-cost FireWire based DV equipments will create momentum on its own.