AAPL provides a document that can be a great help to anyone who is trying to produce web content that will look good on the iPhone. Perhaps the most relevant part of this document is its discussion of the viewport, and perhaps the biggest takeaway from that discussion is the idea that, as a starting point for building mobile-Safari-compatible webpages, you should add this line to your HEADs:
<META name="viewport" content="width = device-width">
