Folklore.org has the full story of how Steve Jobs convinced Bill Atkinson to give the Mac OS rounded rectangles as they were developing the first versions. I won't ruin the story, but if you played with early versions of Windows you may remember it had sharp corners, not rounded ones. Rounded rectangles have been a design concept at Apple for a very long time for a reason.
So it was largely unsurprising to me that Apple just received a design patent for rounded rectangles -- although these are for hardware, not software
