[tomsem]

You can get reasonably good resolution and pressure sensitivity with Wacom Creative Stylus or Adonit Jot. They use Bluetooth to add more pressure/position data. Applications have to integrate the respective SDKs to add support, and there are only a few dozen that do. But these include offerings from Adobe, Autodesk, and others - both vector based and pixel based - so there some good options available. At least it is better than just bare iOS.

Apple could add this to iOS easily enough, then it would be up to Wacom and Adonit to supply 'drivers' for their hardware. I think apps would still have to specifically work with new iOS APIs, but it would probably just be an extension of existing ones with additional parameters and events. Of course, Apple would want to sell you their own overpriced stylus. And they would have to invent a story about how Steve Jobs always wanted to do this, except the technology just wasn't mature enough.

The interesting thing would be if they added mouse/trackpad support (i.e. introduce the concept of a cursor). Then you could (as with Android or Windows tablets) have full control over things without having to touch the screen, which may not have the most ergonomic placement. Apple is not so much into 'hybrid' devices but obviously there are a lot of people with iPads with keyboard covers, etc. and it would be more productive still with a built in trackpad.