Quirks

Controls

• one finger movement scrools page
• pressing and holding the screen displays an information bubble about the page
• scroll wheel events are accessed via two-finger movement

HTML

• 10MB maximum

A bunch of test can be found at John Allsop's iPhone Tests which show that the iPhone's Safari is not the same as the beta released for desktop computers.

JavaScript

• 10MB maximum
• 5 second maximum runtime limit

Fonts

See http://daringfireball.net/misc/2007/07/iphone-osx-fonts for a list of supported fonts

QuickTime

• automatically invoke full screen video playback.
• Apple recommends low-bitrate versions of QuickTime media, and use the iPhone setting for QuickTime export