Platinum is also the name of
Apple's "
Classic"
appearance (window shading, grey
Finder bar, the Apple Menu, etc). The traditional appearance appeared in all
OS's (
Systems) before
OS X. The new appearance is called
Aqua.
Platinum is thusly named due to it's dull grey color, but in all OS's above
8.5 (or
8.1 if you have
Kalidescope), you can "
skin" them by applying custom themes. This is an
appearance manager function. You get this for free if you use the appearance manager
API when writing an app.
Mac OS has looked the same for ages. It is a huge risk for apple to change it now.