Kaspersky Labs is warning of a new worm seen in the wild that is specifically targeting Facebook and MySpace users. The new worm works like several others we have seen in recent history, using infected clients to send messages to other users and prompting them to download a dangerous file. Due to the fact the messages appear to be coming from a friend of the person or at least another MySpace/Facebook user, people are more likely to be fooled by the ruse the worm puts up.
Given that large amounts of the MySpace and Facebook population are likely people who aren't very tech saavy, it seems logical that many of them would be fooled. The worm pretends to be an update for Flash. The purpose of infection is to use the machine as a zombie on a botnet, so even after infection most people will probably be unaware they are infected until they scan their machines. Friend or not, always be careful when anything asks you to launch a program.