Facebook announced launch of Anti-Virus Marketplace with partners Microsoft, McAfee, TrendMicro, Sophos, or Symantec for all Facebook users. AV Marketplace enables people to download full versions of anti-virus software for six-month subscription without any charge. However, Microsoft SecurityEssentials will remain free, though it can be downloaded from Microsoft page as well. You can access the AV market using the direct web link http://on.fb.me/FBAVMarketplace
Additionally these companies will share educational materials on the Facebook Security page. You just need to Like the SecurityPage to receive these updates.