I recently had the pleasure of configuring (playing with) an iPad for a client. The iPad itself is a beautiful device and I'm sure there are many useful things you can do with it. For one, the ActiveSync for email works great with Exchange server. Configuring the 3G service was a bit of a pain, but that was due to poor instructions from Rogers.
The real problem with the iPad is that it can't run many business applications, even Web-based ones. The iPad does not support Flash or Silverlight content. These are used for many Web-based applications. You don't realize how many applications until you don't have them.
This client is using the iPad as a remote access device for Terminal Services. They have a Windows application installed on the terminal server that can now be used by sales people on the road. So, the irony is, that iPad is a great remote access device for Windows, but not all that useful by itself.
I installed the iTap Terminal Services/RDP client for the iPad and it works very well. I strongly recommend it for $12.