The article is something to be expected from eweek. It is sensationalist and generally wrong when it comes to technology.
Some people do not understand the concept of a shared folder. They do not realize that other people can access the information in it. Some users misunderstand enough to share their entire hard drive. This would be difficult to do in the real world, since anyone could see whan one posts on a bullitin board. It is a problem, but it is at an equal risk to when people accidentally post their credit card numbers online.
The article is formed out of an interview with "Howard Schmidt, a former cyber-security adviser to the Bush administration". He was a technologically illiterate advisor to a technologically illiterate administration. The administration favoured alarmism, and of course favors the RIAA/MPAA, so anyone saying that P2P is a huge security risk will be listened to.