Just so you don't all think I'm being a slug and just printing the above letter to the editor, here's some more information that might be of interest on this subject.
Essentially, there are two levels of FCC certification, A and B. Class A certification for devices used in office environments is easy to get since the vendor does the testing itself and doesn't have to file anything with the government. Class B, which covers devices used in the home, is much more difficult to get, since it requires an independent testing lab to do the work and the FCC to certify the device. Any device certified as a Class B device must carry a sticker with its FCC ID number prominently (which usually seems to mean on the bottom or back) displayed. Class B certification, because of the independent testing and the FCC certification, isn't all that cheap at about $3000 to $4000, according to Tom Hora of the FCC, as quoted in a MacWEEK Special Report on the subject. (Incidentally, if you're interested in this subject, you should definitely find the issue listed below and read the full article - it's an excellent treatment.)
All of the devices I use regularly (and could easily tip over or read the back of) had an FCC ID sticker, but that doesn't necessarily mean that the device is clean because in some instances, the ID number could refer to the case of a hard drive rather than the mechanism, or could refer to a certain size mechanism but be used for numerous different size drives. It appears, from some conversations on ZiffNet/Mac and CompuServe, that some vendors don't even realize they have to get FCC certification, and others may have sold uncertified drives in the past.
I've implied, as does Cliff Wildes above, that the problem is limited to hard drives. Many types of electronic equipment can have problems with radio frequency interference, and even my keyboard, mouse, answering machine, and telephone have FCC ID numbers. My impression is that every electronic device that can create or react to radio frequency interference must be certified if it is to be used in the home.
Perhaps the most important place where RFI can cause problems is on an airplane. Airplane pilots can refuse to allow passengers to use any device that will create RFI, so those two guys in the Apple PowerBook commercial who connect their machines via LocalTalk might be shut down. (Ten to one they're really playing Spaceward Ho! over that impromptu network - I sure would be!) Interestingly, there was some discussion on the nets about a new FAA (Federal Aviation Administration) rule that bans the use of laptop computers with mouses (and the accompanying cords) because the cords radiate interfering radio waves. Needless to say, this is a serious problem on newer planes that do not use mechanical controls. This cropped up as an issue because some dealer advertised that the PowerBook was the only (an exaggeration, of course) legal airborne computer. Although the problem and the ban are real, laptops without mouses or laptops that use an internal pointing device like the Outbound Portable are fine.
If you're concerned about this (as I am - I'm leery enough of airplanes and don't need any more cause for concern such as someone with a DOS laptop and mouse interfering with the plane), you can check on FCC Class B certification before purchasing a piece of hardware. It's a simple question and one which the companies ought to at least know the answer to since it is a big deal in certain situations. You can also check your existing devices by calling an FCC BBS, the Public Access Link (PAL). The phone number is 301/725-1072 and is available all the time, though only at 300 and 1200 baud. The other settings are eight bits, no parity, and one stop bit (8N1). Just hit return a couple of times after the modem connects, and then enter the FCC ID number in question when PAL requests the "CODE." You get five minutes per call between 8 AM and 8 PM Eastern time and fifteen minutes the rest of the day. If you have other questions or want to check on the status of a pending certification you can call the FCC directly at the number below between 2 PM and 4 PM Eastern time.
Of course, as serious as RFI problems can be today, can you imagine the utter chaos and confusion that will result if and when we start using wireless networks for real? I can imagine the conversations: "Hang on a minute, I'm getting a lot of errors on that file transfer, let me move the Mac to the other table..."
FCC PAL -- 301/725-1072
FCC Questions -- 301/725-1585
MacWEEK -- 06-Apr-92, Vol. 6, #14, pg. 38