Is the Lombard a NewWorld and the Wallstreet an OldWorld then, as I think that's when the logo changed on the PowerBooks? Yes, a lot of things identify a NewWorld Mac for me, not just the Rom architecture - I tend to associate NewWorld with the whole colours/roundedness/translucency etc revolution, as well as the death of the rainbow logo and the transition from the old ports to USB/FW, though of course the PowerBooks don't fit in with that if the later G3s are NewWorld.

For some reason I also associate NewWorld with OS X, I guess because that is the other part of the "new Apple" as well as the move away from beige, although of course some of the NewWorld came with as old an OS as 8.1. I suppose I think of all NewWorlds today as running OS X - if I saw a B&W or something like that I would kind of expect it to have X on it. The Platinum interface of OS 9 also fits better with beige-cased Macs, and the rainbow logo still features, whereas OS X looks more at home on the NewWorld designs, whose cases are kind of Aqua-ey

Most of the Intel Macs are in identical cases to the older ones (except the MacBook), so they presumably use the same logos as the older models.
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Main system: custom C2D 2.66GHz tower/4GB RAM/2600XT 512 MB/500GB HD/XP Pro x86+Vista Business x64
Main Mac: Beige G3 minitower (Sonnet G4 500MHz/640 MB DVD/USB/Radeon 32 MB/OS 9.2.2+10.4.11)