Serial number on PowerBooks rubbed out?

Tony Euser needed the serial number of his PowerBook, which is located on the bottom of the case. However, he found that it was no longer readable. Apparently, it had been rubbed off by a combination of the heat of the unit and the rubbing of the case bottom against the fabric of his pants while using it on his lap. This loss can be a problem if you ever need the serial number and do not have it recorded elsewhere.

Garth Martin reported the exact same issue. However, he pointed out that Apple System Profiler lists the serial number (in the Product Information section) - unless you have reformatted the drive.