Can you save and transfer documents to the iPad?
Does the iPad support Microsoft Exchange email?
The iPhone supports Microsoft Exchange mail, it would be strange for Apple to remove this feature when it is already present and works well for me.
Does the iPad support VPN and configuration management?
It is running very similar software to the iPhone, which provides this capability. Configuration management may need more tweaks to support iWork but not much more. VPN is already present in the iPhone OS, there is no reason not to carry this across.
Can the iPad be used for videoconferencing?
There is no camera.
There is a space for a camera that fits the camera in the MacBook Pro - this has been shown in the spares delivered to repair shops. This will probably arrive in version 2, something new to buy for all the early adopters. (Disclaimer, I bought the iPhone 2G and then the 3G and was thinking about the 3GS until the iPad arrived ;-)