It's only iphone 4 to iphone 4 so it's basically useless most of the time.
Should be interesting.
Of course, we'll see what they mean by "open standard" after the recent debacle with Safari's "HTML5 Demo", but I'd like to remain optimistic. Webkit was a nice gift, and hopefully this will be something similar.
I'm quite surprised that it's not at least compatible with the video calls in iChat. 3G will definitely happen, but they have a built-in base of millions of users on iChat that could have helped kick things off.