This one probably isn’t new, but it’s worth noting. An associate recently got this bogus “security warning”. Appropriately named “irony”, the message warns the user that “Security Center has detected Malware” and directs the user to a site where they can download a patch. Click on the image for a full sized version.
The “patch” will install malware on the user’s computer. At least they can’t forge the link as belonging to Microsoft, but this could easily fool an unsuspecting user.