Estonia might be the most web-savvy place in the world. They even cast their votes in national elections online. So it's of interest to people who value the utility and security of web applications everywhere that Estonia seems to be the first place singled out for massive targeted cyber-warfare attacks. Denial of service attacks on their government bureaus, banks, and even their news outlets have slowed their web traffic to a snail's pace.
The Estonia case also shows how easy it is to cause massive panic on a shoestring budget. All you need to deploy a cyberattack is some malicious software, a bunch of zombie computers distributed around the world, and an Internet connection. Sure, you may need to pay for a "professional-grade" botnet—a network of computers that have been surreptitiously infected to run nefarious software. But surely that costs orders of magnitude less than the price of heavy artillery, battleships, and nuclear submarines.
Imagine all the Spam you see every day in your inbox turned into a weapon of mass destruction. Estonia doesn't have to imagine it anymore.