The brushed metal is not only more pleasing to the eye but functionally superior (increased drag area). The question is when will Apple switch out the god-awful Aqua stripes for brushed metal everywhere?

I heard from a friend who is an OSX developer, that alledgedly the apps that use the metal (iTunes, etc) are doing so because they are 'virtual' devices, mimicking functionality of some future industrial-designed object --- picking up on the Powerbook style of industrial design, and perhaps signaling some future movement of Apple into more mainstream CE products like phones, tablets, PDA's etc. If they choose to go into this market of physical products they will pick up their established interface vocabulary from the brushed metal apps.

This is what your developer friend was referring to - Apple's Human Interface Guidelines (HIG) for Aqua, specifically this bit on textured windows (aka. the brushed steel look).

I quote:

"This appearance may also be appropriate for applications that strive to re-create a familiar physical device—the Calculator application, for example. Avoid using the textured window appearance in applications or utilities that are unrelated to digital peripherals or to the data associated with these devices."

What digital peripheral is Safari recreating? Apple has sometimes played it prety loose with their interpretation of their own guidelines. It's all moot, though: I still don't like it. :)