http://www.aircraftspruce.com/catalog/elpages/fiberlitelabels.php
Could be handy for some simpit uses.
That's really neat stuff, but pretty expensive once you buy everything required... I doubt I'll be making illuminated labels for my panel, but have considered using fiber to light the whole panel, if I can find a low-cost solution.
But using Spruce's lighting parts I think it would be easy to make one's own label strips: just use P-touch labels or even paper labels sandwiched between thin sheets of clear plastic.