mesaflyer check out www.heliproz.com and do a search for glow wire (I think that is what its called) or do a search on google their is a number of new and old products just for night flying. BTW if you realy want to get into this check out some of the foam airplanes that are for night flying VERY COOL STUFF I'm planing on doing it for next years fun fly.
One last thing Align makes the glow wire for helis but I think they would work for airplanes.