At present Symantec Endpoint Protection 12.1 RU2 (and above) can support Windows 8 Standard and Windows 8 Professional.  Symantec Mobile Security 7.2 can support Windows Mobile 5 through Windows Mobile 6.5.  There is, however, no Enterprise release of AntiVirus software for the new Windows 8 RT platform.  (Windows RT is the ARM-based platform upon which Microsoft Surface, Samsung ATIV Tab, Lenovo IdeaPad Yoga 11 and other similar tablet products run.)  

Symantec Endpoint Protection Product for Windows RT Platform
http://www.symantec.com/docs/TECH199979 
 

Customers interested in a Enterprise solution for this new platform can make their voice heard by voting in favor of this proposed Idea.