I mourn the death of Aqua. It's become fairly obvious that the life ofMac OS X will continue without it - Aqua is slowly dwindling outof Apple's programs and OS X.
Birth
Aqua was born when iMovie 2 came out. This was still in the Platinumera of Mac OS 8 and 9. The next trace of Aqua showed up withiMovie's music-playing brother, iTunes. This was in the late days ofOS 9, and it was becoming fairly obvious this was going to be theuser interface of Mac OS X.
The Aqua-striped menu bar as seen in the OS X Public Beta.
Then Steve Jobs made it official at Macworld 2000. With itspinstripes and smooth curves, Aqua complemented the iMacs, Power Macs,and iBooks of the time. And as Mac OS X evolved, Aqua evolved withit.
Life
In Jaguar (Mac OS X 10.2), the changes were subtle, flattening outsome of the icons and removing some of the pinstripes.
A Finder window in the OS X Public Beta - very obvious stripes.
In Panther (OS X 10.3), the changes grew much more noticeable. Thenew changes added the brushed metal look of the then-new Safari tocomplement the PowerBook G4 and Power Mac G5. There were new iconsacross the whole system, transparency was much toned down, and theFinder was totally redesigned.
Even the Dock has had strong Aqua stripes, as in this image from the OSX Public Beta.
Not much was added to Tiger (OS X 10.4) from Panther beyond a new,toned down Apple icon.
Death
Aqua got put on life support when iTunes 7 cameout. iTunes sports a new look with rubbery scroll bars and a plainmetal look. All of Apple's new applications, including iLife and iWork,have begun sporting it.
iTunes 7 shows Apple's new, as yet unnamed user interface. Expect it tobe everywhere in Leopard.
The iPhone doesn't have single trace of Aqua in it! And all of theLeopard betas for the few last months use the currently unnamedsystemwide look of iTunes.
I will miss Aqua and will enjoy using it on Tiger on my iMac G4/700 MHz, which is apparently going tobe unsupported under Leopard, which "requires" an 800 MHz G4 or better(another rant).
Good-bye, Aqua, I hope to see you in another life. 
Further Reading
