Not sure if this is the right place to ask the question, but if say I wanted to make sure my site was cross-browser compatible with Safari on the iPhone, would it be safe to say that Safari for Windows would render the page the same as it would be rendered on the iPhone?
I would just test it on the iPhone itself, but I want the added tools of Safari on Windows for testing.
You can do the main development on Safari Windows, but you will still need to test your Web site on the iPhone itself because there are some differences between both versions.
I don't know what your Web site is and how large it is, but you may want to consider creating an iPhone specific version of your Web site because screen size is different and file caching on iPhone doesn't work the same way as it does in a Windows browser. So you may want to keep loading time in mind.
Also, you should keep in mind that if you were to make a second version of your site (eg. "m.X.com" in addition to "X.com"), you'll then have two different sites to maintain. Even if the majority of the content is fed by a web app, the majority of the HTML that isn't will need to be changed twice every time you want to update your site (once for "X.com" and once for "m.X.com")... Just another thing to keep in mind.
There are a few other tools to use for iPhone web dev, but they don't always render exactly how it would on an iPhone, so all final testing should always be done through an iPhone.
Those tools are: 1. [downloadable] iPhoney (http://www.marketcircle.com/iphoney/) 2. [web-based] iPhoneTester (http://iphonetester.com/). If you Google "iPhone tester" you'll get a few different similar tools.