Also amusing: "Why The Google Era May Be Over"..."Google is not as bad off as it might seem".
In any case, if you look closer, you then see that the peak growth rate of searches in the last two years was only six months prior, and you start to realize why reporting on graphs looking through a one month window is stupid.
Personally, I would think that many people peaked in personal search years ago (there's only so many you can do in a day). What we're seeing is probably largely driven by population growth and expanding internet access.
For example, when i have programming questions, my first place to look is StackOverflow as opposed to Google. or for restaurants I look at Yelp or Urbanspoon.
In other words, is search traffic just becoming more fragmented across different sites (Yelp, Amazon, StackOverflow, etc.) and apps?
My understanding though was that Apple's relationship with Microsoft was covering that (see this : http://news.cnet.com/8301-13860_3-20006971-56.html) while tentative it seems another tie to Google that they probably don't want.