iPhone, for the first time in history, escliped RAZR as the number 1 consumer phone sold in the U.S. A pretty significant feat considering this phone is a more complicated device with excess baggage of expensive data plan associated. To me, this means that we can expect a mass market hysteria and expect every vendor, retailer, ecommerce giant to step up their web game with an iPhone-friendly website.
Apple has a nice little "Designing Content" packet available here for you to get some basic knowledge on how to build a site for iPhone users (handling application launch, GMAP links and Phone App launch. In their, they explained the "viewport" concept on how pages should be handled for scaling and etc... Its a short read for any marketers or IT personel to get their mindset into an iPhone friendly site. I ran a quick test on Omniture version 14 and saw over 4000+ visitors came to one of our sites via iPhone+iPod touch... thats over 60% of mobile visitors used a mobile Safari device.