"The characteristics of such a market are yet to form," said Ryan and Plzak in their paper, Legal And Policy Aspects Of Internet Number Resources. "It could, for example, result in delivering 'windfall' profits to those who early on obtained legacy address blocs. Corporate assets will instantly be more valuable if they have such blocs as 'assets.' "

Karl Auerbach, former member of the board of directors of ICANN, former Cisco researcher, CTO of InterWorking Labs, and an attorney, happens to be someone who obtained a legacy IP bloc back when professor Jon Postel ran the Internet.

"I've had people who want to acquire my spaces, some for some pretty hefty amounts," Auerbach said in an e-mail, noting than the legal status of IP numbers remains muddy. "Those deals fell through due to uncertainty about whether routing ISPs would honor the deal and accept routing announcements. Without the cooperation of the ISPs, an attempt to transfer space can be futile."

Auerbach said he has loaned IP address numbers to friends on a short-term basis. "But that kind of thing is from the spirit of the Internet of the '70s and '80s but certainly not the commercialized Net of today," he explained. "But don't 'cha think that in many ways the old ways are a nice residual from a more halcyon and more cooperative era?"

As for making a legitimate market for IP address space, Auerbach supports the idea. He also agrees that IPv6 transition won't be easy.

One controversial method for dealing with the IP address shortage has been the increasing use of Network Address Translation (NAT), which effectively creates a private network within a given IP address.

"The issue of NATs has been underappreciated -- they are awful things that cause great trouble," Auerbach said. "But we've learned to live with 'em and new protocols are even being designed in anticipation of NATs. So perhaps the Net of the future might evolve as an IPv4 public mesh connecting private spaces behind NATs. For that we have enough IPv4 space for decades. That scenario runs into trouble when those private spaces try to directly interconnect. But, like Scarlett O'Hara, most of us will think about that tomorrow."