Apple had originally promised that this functionality would be present in the iPod touch, but then withdrew the claim. It was widely assumed the company did so to create a clearer distinction between the iPod touch and the iPhone, which already has Calendar, Address Book and Notes functions.
The only way to add or edit entries now is to make them in Address Book or iCal on the Mac (Microsoft Outlook on the PC) and then synchronise them to the iPod touch via iTunes - hardly a user-friendly solution.
Jobs allegedly made the 'promise' in reply to an iPod touch owner's email, which was then posted on to the MacRumors forum. The email poster - davidjearly - stands by his claim that the email from Steve Jobs is genuine. Certainly Jobs has been known to respond to emails from Mac users, so who knows?
iPod touch keyboard
There's certainly no reason why the iPod touch couldn't enable you to add and edit Calendar and Address Book entries, as it uses the same virtual keyboard as the iPhone. The addition of a Notes application for the iPod touch would be useful too - another point of distinction between it and the Phone.
We're currently verifying whether there is any truth to this rumour. We will, of course, keep you up to date with any developments.