Apple has now confirmed via its Mountain Lion upgrade page that previously published limitations on some 64-bit Macs will extend to the final release. This means that several otherwise 64-bit capable MacBook Pros, iMacs, and Mac Pros will indeed be restricted from upgrading to OS X 10.8 when it goes public later this month. And according to information found in the recently released golden master (GM), the limitation appears to be related to graphics, as we originally suspected.
via Confirmed: Mountain Lion sends some 64-bit Macs gently into that good night | Ars Technica.
