Buckeye is right. Read the patent, read the claims. Patents are awarded all the time for novel methods of performing known functions. Sure, page up and and page down has been used for years. But if Microsoft devises a new method of "calculating offset" (which is positively recited in the claim language)...then cheers to them. They even go on to cite their equations and calculations in the independent claims! In the world of patent rights, this greatly narrows a claim's area of coverage. Please note, that none of their claims are so broad as to cause patent infringement from already developed keyboards. They even disclose that pageup and pagedown keys were known in the prior art in their "Background".
Sparky, they patented a novel method of using such keys. Not the general function. They hardly "own" the keys...like I said, they cite that the original function of those keys were already known. The patent actually has little to do with those keys, and is a method for calculating the vertical offset of a page in order to accurately jump to the next page based on a user input.
However, the patent system is somewhat broken, especially in the field of software engineering. There is NO comprehensive database comprising what is "the current state of the art" in the open source world. This creates a rift between what is known, and what can be proven as known. The courts need documentation of what constitutes the "prior art". If some hack creates a useful program in his basement, uploads it to the internet, and a small user base implements it....well it is KNOWN, but its hard to prove that its known, especially before a certain point in time, ie when the applicant files for his patent.
Anyways, I could go on and on....but this article is very flawed and propogates some serious misconceptions about Patents and IP law.