The Armatix iP1 handgun is a "smart gun," a term that's used to describe a weapon that only works in the hands of a single designated individual; in the iP1's case, that person has to enter a PIN code into a special watch before firing. The pistol is ready for sale, but no one is selling it: in the past month and a half, two stores have decided to offer it before changing their mind due to backlash from gun-rights activists (including the anonymous death threats that no American political discussion can apparently do without). What's motivating Armatix opponents is a law passed in 2002 in New Jersey. The Washington Post's Michael S. Rosenwald, who's been all over the story, explains:
Besides reliability in the face of danger, the opponents’ most pressing fear is that sales of the iP1 will trigger a New Jersey law mandating that all handguns in the state be personalized within three years of a smart gun’s going on sale anywhere in the United States. Similar proposals have been introduced in California and Congress.
An entire state banning the sale of guns that don't have "smart" technology would presumably be a big blow to what gun enthusiasts see as their Constitutional right to fire whatever kind of gun they want to fire in whatever fashion they see fit.
The Maryland store that said it would offer the iP1 just changed its mind last night; the Oak Tree Gun Club in California actively promoted sales of the iP1 in February but stopped soon after receiving press attention. And there's apparently been no movement in New Jersey toward enacting the provisions of the 2002 law even though the conditions it describes seem to have been fulfilled by the iP1's brief availability in California.