After doing some tests and reading some blog posts about the iPhone, someone pointed out to me a link which if you go to it on your iPhone http://www.apple.com/trailers/iphone/ you will see the same trailer page as normally on your PC but when you click on a trailer you get a iPhone formatted page (example). Now when clicking on the trailer at the top on the iPhone it launches the video player that the iPhone uses and the video start streaming in (if your on wifi).
Of course this is pretty neat especially if your connected to a wifi hotspot but doing any sort of streaming over EDGE (at least from our tests) things are slow, buffering, hangs in the trailer etc. If you want to stream over EDGE your going to greatly reduce your quality event to the point where your seeing just a macro block slide show with lots of latency/buffering.
I put together a iPhone demo page to test out a video I encoded here. I recommend loading this on wifi connection, but would be curious to see how it runs on EDGE for some people.