Yes this is no Joke. FBI issued a warning of a trojan that has infected millions of computers around the world.
According to the FBI July 9th is the day hackers intend on shutting down the internet for anyone who has been infected with the DNS changer virus.
Hackers have created a Trojan/virus, which will install itself on the computer and stays there until July 9th. The Trojan virus is set to execute on July 9th. Thus Trojan will deflect all the Internet traffic to hacker's infected servers whereby blocking the access of the Internet.
They advise that before July 9th you run a free check to make sure your computer has not been infected.
You can visit the site here http://www.dns-ok.us/ to run the check. Also go to http://DCWG.org.
If the image below is displayed when you reach the test site you will not be impacted by the shutdown.

If you would like to know more about this nasty virus you can visit the official FBI sit here http://www.fbi.gov/news/stories/2011/november/malware_110911
**** The Back Story ****
Just over three months from now, hundreds of thousands of people could be shut out from the Internet by a computer virus, which links to a serverthe government seized after a two-year operation but they're still shutting down.
The FBI has warned that the virus will start affecting computer users on July 9, saying warning that hundreds of thousands of computer users will no longer be able to access the internet if their computer is infected with a virus called "DNS Changer."
According to the FBI, PC and Mac users face their own personal Internet doomsday unless they disinfect their computer.
This virus first popped up in 2007 and infected millions of computers. Last November, the FBI arrested six Estonians who were running a new operation. So, now that the FBI knows who was doing this, they plan to shut down certain serversthis virus was directing people's computers to.
This means if you don't clean up your machine by July 9th, your computer will be trying to ping a server that has been turned off by the government.
As of February, half of all Fortune 500 companies owned computers infected with DNS Changer virus.
Full FBI media release:
http://www.opednews.com/articles/Remember-FBI-Warning--Aft-by-Jack-Swint-120702-735.html