On the market for an iPhone? Here's a breakdown of all the currently shipping iPhones from Apple.
New HTML and CSS Features in Safari 3.1
CSS Animation - transitions, and animations allowing you to do CSS-based animations and Transforms. (example above from Surfin' Safari)
HTML5 Media Support - New 'video' and 'audio' tags that allow you to embed video/audio content easily. Example video embedded here.
Downloadable Fonts - instead of having to rely on common fonts available to browsers, you can link to actual font files within your CSS. For example, this html page takes advantage of web fonts and will render differently depending on which version of Safari you are using (more examples and explanation):
Safari 3.0 on the left, 3.1 on the right.
Other features include native getElementsByClassName and client-side database storage.