Apple as a new user guide with a interface designed specially for the iPad. The user guide looks very similar to the settings screen on the iPad. It covers the original iPad and the iPad 2 with the latest iOS 4.3 features.
The guide has a user agent that detects if you are on an iPad, if you are using anything other than an iPad it redirects you to a PDF.
The interface is so nice I recommend bookmarking the page and adding the icon to your home screen.
The user guide can also be download for free with iBooks or you can view the PDF on the Apple website.