Refer here - http://en.wikipedia.org/wiki/Inventive_step_and_non-obviousn... - "One of the main requirements of patentability is that the invention being patented is not obvious, meaning that a "person having ordinary skill in the art" would not know how to solve the problem at which the invention is directed by using exactly the same mechanism."
Predominately - "that obviousness should be determined by looking at the scope and content of the prior art; the level of ordinary skill in the art; the differences between the claimed invention and the prior art; and objective evidence of nonobviousness. In addition, the court outlined examples of factors that show "objective evidence of nonobviousness". They are: commercial success; long-felt but unsolved needs; and failure of others."
See also - http://en.wikipedia.org/wiki/Title_35_of_the_United_States_C....
Again - this article is attempting to state "oh because PDA existed, that means that everything related to a device with a touchscreen and few buttons was obvious". but again, thats untrue.
I still believe - in additional the complex legal arguments - the comment below was one of greatest aspects that changed the lay-persons juror mind. Per the Apple lawyer Harold McElhinny
"In those three months, Samsung was able to copy Apple's 4-year investment in the iPhone, without taking any of the risks—because they were copying the world's most successful product ... No one is trying to stop them from selling smartphones, all we're saying is: make your own. Make your own designs, make your own phones, and compete on your own innovations."