The above video shows the folks at 9 to 5 Mac testing out Pages, an iPad App, on the iPhone 4. It seems to run pretty well, actually. As they point out, much like Netflix streaming on the iPhone, this App doesn't look bad when run on something smaller than the iPad.
The website does point out that though there is no sign of Pages coming to the iPhone in the near future, if at all, it does seem to run well and they seem to hope for a similar outcome to what happened to Netflix, when an official iPhone App was shown at WWDC 10.
Still, we don't remember seeing a presentation of the actual streaming during the keynote, and the App was announced to be in development back in April.