MacDefender is the first piece of authoritative looking scareware to target Macs.  Scareware is a term for fake security software that once downloaded causes frequent popups that claim your computer is infected and that you must buy the full version to remove the bugs when in fact the alarms are bogus and the program is worthless.  On Tuesday Apple promised an update to the Mac OS that will help Mac owners find  and remove the fake software program.

Via: computerworld.com