Multitasking is a feature of iOS 4 that allows applications to perform specific tasks in the background while you are using other applications. Multitasking in iOS 4 is supported on iPhone 4, iPhone 3GS, and iPod touch (3rd generation).

It is important to create frequent backups of important data. This is even more important if you are using beta software. You should make sure you back up your data prior to entering the MobileMe Calendar Beta.

You can view and share files on your iDisk with the iDisk app for iPhone, iPad, and iPod touch. For help using the iDisk app, open the app, tap Settings in the upper-left corner, then Tap iDisk Help.
If you encounter issues while using the iDisk app, the steps below can help you troubleshoot further. iDisk [...]

By downloading VoiceOver Kit to your computer, your iPod will announce the names of your songs, artists, and playlists. If you no longer wish to use the VoiceOver feature on your iPod and want to remove the VoiceOver Kit from your computer, follow the steps below.

You can purchase the iOS 3.1 Software Update for iPod touch (1st generation) from the iTunes Store using the latest version of iTunes on a Mac or PC. 
Purchase the iOS 3.1 Software Update directly from the iTunes Store.
Own an iPod touch (2nd generation or 3rd generation)? Get the free iOS 4 Software Update for iPod touch.
If [...]

Immediately after updating to iOS 4, some users may notice that Exchange ActiveSync Mail, Contacts, or Calendars do not sync, or sync very slowly. In addition, some Exchange Server administrators may notice their servers running slowly.

On iPhone, iPad, and iPod touch, you can save images from a variety of applications (such as Safari, and Mail) to your device. With your iPhone, you can also capture photos using the built-in camera and video footage* with the iPhone 3GS and iPhone 4. The following document will help explain how to import this [...]

If you are having issues with an iPhone, iPad, or iPod touch accessory, try the following troubleshooting steps:

iOS 4 devices are unable to resolve unicast DNS names that end with a “.local” suffix, affecting access to internal corporate networks that use an internal, top-level domain name, such as “mydomain.local”.

Learn how to reset or restart iPod following a freeze.