Most of these are not that obvious to me but the Edit button in Mail is useful as is saving images from the web
E-mail Management: You can now mass delete or mass move e-mails in the Mail application. Just tap the Edit button in the top right of the interface to call up the controls.
* E-mail Attachments: The Mail application expands its attachment abilities with support for iWork and Microsoft PowerPoint files.
* Image-Saving: It’s now simple to save images from Web pages or e-mail attachments by tapping and holding the image. You’ll get a message asking if you want to save it, and the saved image will end up in a new iPhoto folder.
* You can also take a screen shot of your desktop by quickly pressing the sleep/wake button and the Home button at the same time.
* To end .net, .com or .org, press and hold the .com button or if there is an @ sign on the keyboard, press and hold the period “.”