Yes, bought a DVD ROM especially to boot Panther. Which was shipped with a 17" G4 PowerBook. It installs fine on my old G3 PowerBook though, so I guess its 'Product Line Specific' rather than machine specific.
When Apple restricts its software, it employs various methods. Some requires a certain type or speed of CPU, other stuff (Like OS Installation) looks at the Mac's model name. The Powerbook G3 Lombard is called PowerBook 1,1.
You can check the name of any Mac with Mactracker.
www.charlessoft.com/
I guess Panther looks at the PowerBook part, and ignores the 1,1 part. The G4's have different numbers.