iOS 4.2 introduces several enhancements to Mobile Safari

4.2 iOS arrived yesterday and the update includes a new version of Mobile Safari, which includes many important improvements:

• Better support for HTML5
• Support for the accelerometer and gyroscope. Web applications can now use this hardware.
• Media
• WebSockets support a HTML5 standard.

Apple has not updated Safari documentation to reflect these new APIs but do not take long for developers to start using the benefits introduced in this update.

Source: TUAW