I believe you can chuck any 1TB drive in the primary bay, but in the optical at least you're currently limited to the Spinpoint M8 by Samsung at that size.
I can't wait for it to come out here, I've been trying to get a Samsung M8 here for weeks but nobody in Australia will sell me one, except MacFixit which are claiming it costs ~$220US and selling it for about $170 USD when newegg have it for $89.
Be interesting to see how it compares to the Samsung performance wise.