With or without ext? I'm assuming without so probably not worth much unless the other extension holder wanted it but if thats the case they would have registered it by now you would assume.
So you've got a zipcode nobody has been interested enough in yet to register.
A few things to consider:
1) If nobody else has reg'd it, they didn't think it was a popular enough zip (And there are folks out there that buy them by the handful)
2) But the overture is somewhat good, especially if that was w/ ext (but I doubt it was).
If the .com is still available on a name that has the .net and other extensions registered, I always grab it. Eventually someone will come looking for it IMO.