There certainly is a lot of buzz about Apple's rumored Tablet product. Daring Fireball writes:

If you’re thinking The Tablet is just a big iPhone, or just Apple’s take on the e-reader, or just a media player, or just anything, I say you’re thinking too small — the equivalent of thinking that the iPhone was going to be just a click wheel iPod that made phone calls. I think The Tablet is nothing short of Apple’s reconception of personal computing.

What I find most interesting are the view that the Tablet may bring new computer interaction paradigms. Again from Daring Fireball:

Our “desktop” computers’ human interfaces haven’t fundamentally changed since 1984 — keyboard and mouse/trackpad for input, overlapping draggable resizable windows on-screen, and a hierarchical file system where you create and manage “document files”. Have you ever sat back, scratched your chin, and wondered when the computer industry will break free of these current interfaces — which can be a hassle even for experts, and downright confusing (e.g. click vs. double-click) for the non-experts? Surely no one expects the computer interfaces of, say, 50 years hence to be based on these same metaphors and input methods. What’s the next step?

A touchscreen tablet isn't really suited for the WIMP paradigm as for example text entry is quite difficult, and you probably want larger, thumb-friendly user interface elements. This is where Microsoft's Tablet PC initiative failed, trying to bring the regular WIMP user interface to the tablet.

Instead what seems to be happening is that all the Wiis, iPhones, and N900s are now heading us towards a post-WIMP world. Instead of indirect manipulation by mouse and keyboard we can now interact with our applications using the more natural ways of touching things on screen or moving the device around.

This innovation will not be limited only to mobile APIs, web applications can already now know whether user is accessing them via a WIMP system or a touchscreen device thanks to CSS media queries and Javascript orientation events in latest Firefox.

The user interface innovation that is arriving thanks to these new interaction possibilities is quite promising, though it will probably take a while before we know what things actually work, and what are just fun demos.

If you're thinking about new kinds of user interfaces, it might be a good time to read papers like Noncommand User Interfaces (Jakob Nielsen, 1993) and Magic Ink (Bret Victor, 2006).

I certainly am as we are in the process of defining a new kind of CMS UI for Midgard 2.

Update: Gizmodo has a very nice article on Jef Raskin's information appliance concept and the evolution of GUIs.