The idea that "Wikipedia is a brain extension" has been around awhile, and XKCD writes about it all the time—
Now a NYTimes editorialist loves offloading mental tasks onto technology:
Memory? I’ve externalized it. I am one of those baby boomers who are making this the “It’s on the Tip of My Tongue Decade.” But now I no longer need to have a memory, for I have Google, Yahoo and Wikipedia. Now if I need to know some fact about the world, I tap a few keys and reap the blessings of the external mind.
Personal information? I’ve externalized it. I’m no longer clear on where I end and my BlackBerry begins. When I want to look up my passwords or contact my friends I just hit a name on my directory. I read in a piece by Clive Thompson in Wired that a third of the people under 30 can’t remember their own phone number. Their smartphones are smart, so they don’t need to be. Today’s young people are forgoing memory before they even have a chance to lose it.
This is actually a very old trend. In the early roman republic, messages were sent by telling a story to the messenger, who'd remember it and tell it back at his destination: before writing was common, people had crazy powers of memorization—they could put away megabytes of epic poetry without much effort, etc. Tribes on the northern outskirts of the republic warned their students not to learn to write because it would impair their ability to remember—if you store your thoughts on the outside (on paper), you get worse at storing them on the inside.
About a year ago, Harper Lee (To Kill a Mockingbird) said, "Now, 75 years later in an abundant society where people have laptops, cellphones, iPods and minds like empty rooms, I still plod along with books. I prefer to search library stacks because when I work to learn something, I remember it." I took offense at the time, but she has a point: plugging in is a trade-off, like it's always been.