This tool lets you enter a Mac’s serial number and it will tell you where and when it was manufactured. Here’s what it says about my 15″ PowerBook:
serienummer: W84177AWQHY Code: QHY Model: Mxxxx PowerBook G4 1.5GHz 15 inch Drive=SuperDrive Factory: W8 (China) Production year: 2004 Production week: 17 (1083193200) Production number: 9501 (within this week)