Why bother someone asked? Because I think we are witnessing an
important inflection in the development of computing. It's also fun to
measure ourselves against Apple's brilliance; how surprised are we by
the result, how good are our predictions? Here are mine:

I think the most important consequence of this device will be an extra
boost to the process of application redesign that has been ongoing
since the introduction of the iPhone multitouch screen.

Specifically I think it's the direct interaction (think FlightControl)
which is important about these devices rather than multitouch.

The hardware has been discussed a lot, so let's have a think about the
interface.

Beefier, faster device so we perhaps application multitasking of a
handful of applications. That means there needs to be some visual
device for switching between apps. Or perhaps a button and an exposé
like affair.

Managing windows is a pain, so I expect all apps to be full screen.
Some areas like the switcher, the status indicator and in most apps
nav bars will be walled-off by convention as before.

There will be a new larger content area and this will have the most
long term impact. This screen will have enough space to be useful for
practical tasks as well as casual gaming and media consumption.

What apps will we see? I don't know, but I'm sure the community will
have a good go at everything in time as they have with the iPhone and
this device will make a wider gammut possible too. I think it unlikely
that Apple with go with an iWork like suite early on, but there may be
a few little surprises. Photos will be expanded to the point where it
could usher in a nascent iLife suite.

As I walked the length of a train the other day I saw what people were
doing with their laptops. A good amount of media, some document
review; wordprocessing and spreadsheets. Email of course. A few people
were using sophisticated creation apps like logic, flash or an IDE.

It's instructive to ponder how any of these applications might be
redesigned for the hour long journey on the train where one is mostly
reading, reviewing, marking-up and editing. Spreadsheets needn't
involve a lot a great deal of text entry.

Once the door is open I expect a great deal of experimentation within
the envelope of the device; let's say 140 characters is about the
limit of text one can be bothered to type on it ;-)

API wise we can be sure we'll see the same Darwin/CocoaTouch layers as
before, simply a new shell.

Also the Application model still be in place. There's no other
prevalent model for building software and Apple is going great guns
with the AppStore

A few words about the hardware. We can assume the focus of the device
will be media, video, music with apps coming in second and books as an
interesting new avenue.

However I expect Apple to go with a fast bright screen suitable for
flicking and browsing rather than a long-life highly-reflective eInk
style screen. It might however adopt something like Pixel-Qi's hybrid
screen. These screens tend to be a bit dull (though practical) and
don't play so well at the point of pickup in a store, Apple's forte.
You wanted it before you walked in the store, picking it up just seals
the deal. So I expect the screen to major on 'gorgeousness' and less
on energy efficiency and reading practicality.

Concluding, this device will be much more interesting than we might
guess at. I expect it to usher in an era of application redesign to a
more intimate and direct experience than the desktop. This will also
be orthogonal to the local/gears/browser/cloud transition that is
going on.