I don't see how Apple could actually get away with patenting 'multi-touch'.
I mean, in the broadest sense of the term surely it means being able to interact with the screen in more than one place at a time, i.e. with more than one finger on the screen?
Since more and more technologies and systems are moving towards touch screen interfaces (on screen keyboards, etc) how could they grant a patent to Apple preventing anyone else from using more than one finger on the screen at any one time? Surely that would mean every other company that developed something with an on screen keyboard would only be able to allow the user to touch one key at a time (unless they licensed the technology from Apple). It's rediculous and would be so prohibitive to any technological advancements.
I don't see that there's any way such a patent could be issued.
Leaving aside that Apple isn't trying to obtain such a broad patent (as they weren't the first to invent touching the screen with multiple fingers), the whole point of patent law is, yes, the patentee has an exclusive monopoly to the technology. No one else can use it without the patentee's permission.
On the one hand, yes, that would seem to foreclose technological innovation. On the other hand, though, it helps technological innovation as companies and inventors are more willing to put in extensive work to develop a technology if they know that at the end they will receive a 20 year monopoly on the technology.
For example, a pharmaceutical company is less likely to spend billions to develop the cure to cancer if, after they spend all that money, everyone is free to copy them.
The trick is to try to set the duration of patent protection, and to set the level of innovation necessary to obtain the patent, to the right levels so as to encourage the progress.
In your example, if, for example, Apple was granted a patent to "multi touch," it is unlikely that their competitors would just give up and go home. They'd research alternatives (gesture-based input, speech input, mind reading, who knows), and perhaps we'd be better off than everyone just simply doing multi touch also.
