Do people just scale down the 2x icons to create the 1x series or actually change the icons (emphasizing certain aspects in the 1x version)? Based on my experience on the rMBP, it seems as if the icons are actually different.
The people who currently care about retina-friendly graphics tend to be those who have long cared about carefully hand-tweaking every variant-scaled version of every graphic they produce.
But as hi-dpi concerns become more mainstream, I doubt there will as much overlap and we'll see a lot more naive scaling.
I just use SVG for all icons, so I don't have to worry about it. I design them on a low-DPI display and am usually pleasantly surprised when I check in high-DPI.
