Like that’s how most people start fighting because that’s how most of the fights in my school happen — because of some Facebook stuff, because of something you post, or like because somebody didn’t like your pictures.

– A middle school girl who took part in the Pew study “Teens, Kindness and Cruelty on Social Network Sites”

Interestingly, though, growth in e-readers has actually accelerated in the last six months, while tablet growth has been relatively flat in recent months after enjoying a steep ramp-up following last year’s launch of the iPad.

According to a study conducted by the Pew Internet Project, the number of adults in the U.S. with a Kindle, Nook or other e-reader doubled between last November and this May, to 12 percent from 6 percent. Tablet ownership has grown three percentage points in the same timeframe, from 5 percent in November to 8 percent as of May.

“This is the first time since the Pew Internet Project began measuring e-reader use in April 2009 that ownership of this device has reached double digits among U.S. adults,” Pew said in its report.

Around 3 percent of adults have both a tablet and an e-reader, the survey found.

Both devices still fit in the nascent category, though, well behind established devices such as desktops, laptops and digital video recorders, each of which is owned by more than half of adults. Some 84 percent of adults in the U.S. own a cellphone.

But we’re not exactly right. New statistics from the Pew Internet Project indicate that 19 percent of U.S. Internet users are on the service on a regular basis. To spell out the obvious: One in five is a lot of people, but it’s not everyone.

This is worth remembering as Google (GOOG) and Microsoft (MSFT) move to integrate Twitter updates into search results: Those results come from a particular slice of Web users.

Here’s Pew’s breakdown of that slice, by gender, race and other demographic markers:

Pew says the average age of a Twitter user is 31 (MySpace, 26; Facebook, 33; LinkedIn, 39). And it has some other stats that are useful–and, if you use the service, evident.

For instance, Twitter and mobile are a peanut butter/chocolate combination–25 percent of Internet users with wireless access use the service, compared with eight percent of those who are tethered. And, not surprisingly, gadget junkies are Twitter junkies too: 39 percent of Web users with four or more Internet devices use the service, compared to 10 percent with one device.

The full report is embedded below:

PIP-Twitter-Fall-2009 –

Yes, there other players in the online classifieds business, and they cut into the monopoly that newspapers relied upon for decades, too. And some of them, like Monster (MNST) and Yahoo (YHOO), have even tried to ally themselves with newspapers. But all of them charged money for their services. And you can’t compete with free. Just ask the music industry.

Craigslist launched in San Francisco in 1996, but didn’t really start picking up steam until the end of the first Web bubble, which is exactly when the newspaper industry’s classified revenue peaked. See for yourself, via this chart from the Pew Internet & American Life Project (click to enlarge):

So 12 years from now our work lives will be our lives entire?

That’s an unsettling thought. But if we’re always connected, always on the grid, then what’s to stop it from coming to pass? What’s to stop “the expansion of the work to encompass all time and all space,” as Nick Carr described it in his comments to Pew researchers. A reassertion of the same boundaries we’re seeing erased, I imagine. Otherwise we may have this to look forward to…

Said Benjamin Ben-Baruch, senior market intelligence consultant and applied sociologist for Aquent: “In 2020…a myth will develop that outside of formally scheduled activities, work and play can be seamlessly integrated in most of these workers’ lives. Employers will attempt to convince us that this is a net positive for people because we will be able to blend personal/professional duties…. However the reality will be quite different. Because we can be surveilled whenever we are ‘connected’ and especially because we can be surveilled whenever we are connected using our employer-provided devices, we can and will be controlled. Our employers will gain even more control over work-time discipline and over our lives and will be able to force even more productive working hours from us. Our lives will in fact be increasingly controlled by those who provide us with the devices that will have become increasingly necessary for us in both our work and personal lives as well as those who own and control the networks and network sites that we use and visit. Some companies will try to distinguish themselves as companies that do not actually use their power to watch and control us–but most companies will do the ‘fiscally responsible’ thing of using available technology to assert control.”