Obviously the biggest news for computer security of the past week is the hacking of Steam. Right now the best thing for the user to do is change your Steam password, and once the Steam forums are back up, put in a new one there too. Also, monitor your credit card information, if you had that information in Steam.
From McAfee’s Threat Activity page we find numerous new Trojans, and all considered a low level threat. Many of these are password stealers but are still considered low level threats likely because they are easy to avoid.
Always be careful about what websites you visit, email attachments you open, networks you connect to.