Answer:
The iPad can run only one app at a time but if you switch apps and go back to the original app (such as Safari) - it will display what you were last doing incase you need to continue that task. However, Apple announced version 4 of the OS iPad uses recently and OS 4 will have multitasking. The iPad will be getting the version 4 update this fall (around October I suspect).
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According to the latest Apple's statement iOS 4 for iPad will be available this coming November. With iOS 3.2 iPad is capable of running pre-installed apps such are iPod (you can listen music, while working with any other app, which doesn't play music), Clock (Timer / CountDown), App Store (app downloading and installing process).