Apple insists in the developer documentation that user should not be aware of files- because it is not the user's role to take care of saving data, storing it at a specific place, etc.
However they do say that iPhone OS 3.2 allows the creation and handling of files.
What's very likely to happen is that there's going to be a shared folder on the iPad, from which the iPad will be able to load and save files even though it will be transparent for the user.
So you'll work on your documents through iWork, be able to send them via email or to your computer, but you won't have to worry about saving them in a specific folder- the apps will do that for you. For instance when you open Pages, it'll show you all your documents present on your device as previewable icons, and you'll just choose the one you want to work on by tapping on it.