MacStories points out there is a small, but perhaps important, difference in the "SSD+HDD" option on the new iMacs. You used to simply get two drives you had to manage separately, as in the screenshot here taken from my MacBook Pro (in which I long ago swapped the optical drive for an SSD). For the new models though, Apple now specifically states: "if you configure your iMac with both the solid-state drive and a Serial ATA hard drive, it will come preformatted with Mac OS X and all your applications on the solid-state drive. Then you can use the hard drive for videos, photos, and other files."
This may suggest
