stevenf iPhone Review
Amusingly, web pages with the most flexible layouts (say a table with a single stretchy column) have the most trouble adapting to the iPhone usage pattern, because iPhone Safari renders the page to a fixed width, rather than wrapping words like most mobile browsers, you'll end up zooming and panning on these types of pages.
While the fixed width presents some drawbacks, the benefits far outweigh them. I've written up an extensive review of those benefits, particularly for web 2.0 application usage here:
http://2glue.typepad.com/productivity/2007/07/mobile-web-20-p.html