http://9to5mac.com/2011/07/20/new-apple-hardware-what-you-need-to-know/#more-84174
Based on the description from Apple And because we place the flash chips directly on the logic board, they take up much less space about 90 percent less, in fact. , it sounds like the SSD is probably no longer upgradable via OWC and others (thanks commenter)
Based on the description from Apple And because we place the flash chips directly on the logic board, they take up much less space about 90 percent less, in fact. , it sounds like the SSD is probably no longer upgradable via OWC and others (thanks commenter)