Steve Jobs's 2007 claim that the new iPhone featured "the real Internet" was a little inflated. While the basic XHTML/CSS rendering of Safari on the iPhone is very similar to the rendering that Safari does on the desktop, there are a few weaknesses:
While many of these weaknesses are disappointing to Web users and developers alike, the key weaknesses from a designers perspective are the lack of support for:
It's true the iPhone is reinventing the mobile experience in many ways, and the user interface of this device raises the bar for all mobile device manufacturers (I remember when I first picked up an iPhone I immediately knew how to use it; this was a distinctly bizarre experience...). But for the iPhone to not support Flash or XSLT strikes me as Apple being sloppy or naive (or both).
You may not know a lot about XSLT, but XSLT mixes XHTML with CSS to provide structure and appearance to XML files in Web browsers. I use XSLT and XML more and more, and expect the future of the web will a bigger place for XML and XSLT than current practice suggests.
Other than these two arguably important elements, rendering a basic XHTML + CSS Web page on the mobile version of Safari is very similar to the desktop Safari experience, however Web designers should immediately notice that fully fluid designs are far more usable than fixed designs, and user control of font size can be a significant advantage on a small device.