Well I spent two hours in Gimp (Like Photoshop) Making this mock up, I wanted to see what a folder Icon would look like. (Hey I haven't used Gimp in ages) I Tried to make it accurate pixel for pixel what it may look like on the retina display. Please don't laugh at my wi-fi symbol, that was near impossible to make, (With my gimp abilities atleast).
EDIT: You have to understand that actual size looks huge on your computer screen, because this is representing a 326 ppi screen.
Actual Size
2X zoom
4X zoom MOD NOTE: timg tags added. Click for large version.
Full Screen (not a mock up)
https://z52yfq.blu.livefilestore.co...Qx4YJZInedxc9sDmmcAnYvWOUsZ/retina.png?psid=1
EDIT: You have to understand that actual size looks huge on your computer screen, because this is representing a 326 ppi screen.
Actual Size

2X zoom

4X zoom MOD NOTE: timg tags added. Click for large version.

Full Screen (not a mock up)
https://z52yfq.blu.livefilestore.co...Qx4YJZInedxc9sDmmcAnYvWOUsZ/retina.png?psid=1