You too -- I gave Taiko a pat for ya!

I've had the same experience as mobydisk, Dave, but lack her technical expertise (and yours, obviously) to deal with it. I've made bootable copies of my iBook drive on two partitions of a larger backup drive. The backups seem to work perfectly, but when I'm in the iBook's drive, both backups have the normally invisible dev file visible. When I boot from either of the backups, that backup's dev file becomes invisible again (a function of the Finder, I guess, as you've explained above), but the other backup's dev file can still be seen -- and copied and (I fear, although I'm not about to risk the attempt) moved or deleted. Meanwhile, the dev file on the iBook's internal drive stays invisible no matter which drive is the startup.
I presume there's a command in Terminal that will reset both backup dev files to invisibility so that some darned fool (likely myself) won't inadvertently move or delete them, but I'm a total and fearful Unix virgin. Should I go there at all? And if so, can you take me through it step by step?

Doug, really, no -- just don't touch the file. Think of it like the "System" folder: don't touch, and don't let it bother you.