Incandescent light bulbs do not produce UV, however, fluorescent do. No where near as much as the sun do though. A quick wikipedia search shows that 8 hours of exposure to fluorescent light is equivalent to 1 minute of sun exposure.
Compact fluorescents put out a small amount of UV (same as what was said above), but it wouldn't be enough to effect fermentation unless you had it the bulb pointed right at it for hours everyday (like, say, in a display cooler in your liquor store). Just having it in a room and turning the light on while you're in there won't do a thing. Toss a towel over it (as was said above) if it reassures you, though.
Someone did a study on ambient room lighting (fluorescent and incandescent) and found that fluorescent room lighting really wasn't enough to worry about, given that (among other things) the very small amount of UV from fluorescents only comes into contact with whatever beer is against the walls of the carboy at any given time.
But I figure, what the heck, it's not a big bother to protect from even that small amount, so I do it.