iOS 5 brings a split keyboard to the iPad. Here's how to use it.
1. Pull up the iPad's on-screen keyboard in Pages or your preferred application.
2. Drag two fingers from the middle of the keyboard toward each side of the iPad's screen.
You can do this in portrait or landscape mode. You can even slide it up and down.
Now you can easily type with your thumbs on your iPad by using the split keyboard. It's sort of an on-screen version of Microsoft's ergonomic keyboard. Not quite the same, but about as close as you're likely to get on a tablet.