Originally named, "Warning: Piko Interactive's Quest Forge Game Carts Might Damage NES Consoles"
Quest Forge from Piko Interactive could cause damage to NES consoles. See http://forums.nesdev.com/viewtopic.php?f=9&t=15240 for the how and the why of the situation. The short story: cheap Chinese circuit boards can cause damage to the NES's circuitry. Supposedly Piko Interactive will be addressing the problem, but I know no more than this.
Perhaps someone with a technical inclination toward NES hardware can summarize things for us less technical types?
Thanks to Gradual Games for the notice.