My retort via the comments:
"The internet isn't the problem, it's just an enabler. People are the problem.
Let's not all pretend that before the internet no one ever multi-tasked, or had a short attention span. The 'net is just a convenient place to fix the blame.
There are a number of widely used internet tools that can actually help you focus more (Remember the Milk for one). I use Google Docs to help me set my weekly priorities (ala "First Things First"). I use Google Calendar to set a weekly schedule that focuses on my priorities and keeps me on track.
Those who are mentally weak will allow the internet to throw them off. Those who are strong, use it for benefit and enhancement. Look to the weak of mind and spirit and you will see the cause..."
For those who will get sidetracked, if it weren't the internet it'd be books, or tv, or magazines. It's whatever. The tool is never the enemy, it is the user of the tool, the craftsman is always to blame.
Nicholas Carr feels our Google-induced pain in an essay for the July issue of The Atlantic: The once-unified attention span has been fragmented, leading us to skim across the surface of information whose depths we'll never penetrate; or else to penetrate straight to some particular depth without passing through all the others—a journey without context or commitment. In the article, Carr asks "Is Google Making Us Stupid?" He doesn't quite answer the question, but it's a good one.
Google isn't really entitled to be the solitary villain in the piece, but because it functions as the Internet's index page it is surely the hub of our Great Distraction. Carr therefore strikes a chord (I was unable to read the piece in one sitting). Of his friends and acquaintances he writes in his essay, "The more they use the Web, the more they have to fight to stay focused on long pieces of writing." Of himself, he writes, "Once I was a scuba diver in the sea of words. Now I zip along the surface like a guy on a Jet Ski."