Design patents are often granted for relatively small changes but then they have a corresponding narrow scope. In this case Page 2 of this design patent D661296 lists all of the prior art the examiner took into consideration. The Sony X505 is listed as well as a couple of dozen other things.
All of those cited references are - by definition - not the same as whatever the patent covers.
In fact, on an Information Disclosure Statement filed by Apple, they brought 26 US patents to the examiner's attention and they listed the X505.
From IDS Apple filed, see #3 in non-patent literature:
Apple does not own the wedge, they own the specific design in the patent drawings. How broadly or narrowly the coverage is interpreted depends on the distance between the prior art and the patented design. (see articles about Egyptian Goddess case) The closer the Apple design is to what came before it, the more narrow Apple's coverage would be. In any case design patents only cover the look of something not the functionality, so the choice being denied to consumers is ornamentation.