The two-face icon for Finder on Mac dates back to the early days of Mac OS, and at this point I think we've all just assumed that it will pretty much always be around. Sure, it's gotten a few tweaks over the years -- with the addition of color and a new glossy appearance -- but the shape and layout of the icon has remained identical to when it originally debuted.
But with OS X Yosemite, the funky face gets a totally new lease on life. Ditching the strike-through slashes at the top and bottom of the original icon, rounding off all the sharp edges and widening the mouth itself. It's an overall more spunky and happy image, and for an icon that has been around for almost 18 years, it's an update that is probably long overdue.