&quot;Mac App Store customers running OS X Snow Leopard (v10.6.8) will be unable to purchase new apps or run previously purchased apps that utilize receipt validation until they install the OS X Snow Leopard update which will be available via OS X Software Update this January.&quot;<p>Note that Mac OS 10.6.8 is the most recent OS version for the Intel Core Duo Macs. 
Those are the first MacBook (early 2006), the first 2 MacBook Pros (January 2006, May 2006), two Mac Minis (February 2006, September 2006), and two iMacs (January 2006, July 2006).<p>It also affects people who keep Snow Leopard 10.6.8 for sentimental reasons. Apparently 1 in 5 Macs use Snow Leopard. Not being able to receive new app updates could be troublesome.<p><a href="http:&#x2F;&#x2F;www.computerworld.com&#x2F;article&#x2F;2487996&#x2F;malware-vulnerabilities&#x2F;apple-retires-snow-leopard-from-support--leaves-1-in-5-macs-vulnerable-to-at.html" rel="nofollow">http:&#x2F;&#x2F;www.computerworld.com&#x2F;article&#x2F;2487996&#x2F;malware-vulnera...</a>