If you consult the Internet Assigned Numbers Authority (IANA) IPv4 assignment page, you will notice that there are no remaining “UNALLOCATED” blocks in IPv4. This comes as part of the chain of events leading up to IPv6 migration and was triggered by the assignment of 179/8 to LACNIC and 185/8 to RIPE NCC a few days ago. These two assignments took the global unallocated pool down to five /8s, just enough for each regional Internet registry (RIR) to get one last block before the party ended.
The IPv6 proponents are using this as a call to action to spur the IPv6 transition. I look at the IANA list and wonder why the “Class E” space is still marked “RESERVED.” RFC 1700 declares 240/4 as “Class E addresses are reserved for future use.” I for one can’t think of a better “future” use for this space than to extend the useful life of IPv4 while we work out the kinks in IPv6. IANA allocated nineteen /8s in 2010 so the sixteen /8s that 240/4 comprises wouldn’t buy the global pool much more than a year. There are also concerns that some existing hardware and software won’t accept IP addresses in the 240/4 range though IPv6 suffers from the same problem.
I tend to agree with Dave Siegel at Global Crossing that the exhaustion of the global IPv4 pool is NOT a reason to panic. It should be used as an opportunity to review your IPv6 plans (You do have an IPv6 plan, right?) and make sure that you are on track. ISPs and RIRs both have a good deal of IP space stockpiled. If you are projecting the need for more IP space in the near future, this is not a good time to procrastinate on your request.