As predicted last week by InfoQ, the IPv4 space ran out in January 2011. A request from APNIC (the regional internet registry for the Asia and Pacific region) for two IPv4/8 blocks has resulted in the final five IPv4/8 blocks being distributed to the remaining RIRs as per RIPE-436.
Although there are some IP blocks marked as “future use” in IANA's IPv4 address space, these were for future developments in the protocol rather than expected to be freed. A chunk of those are in the 1981 reserved experimental class E space, which as well as the multicast class D space, are unable to be used for hosting public facing servers.
From a practical perspective, the RIRs have all the IPv4 addresses they are ever going to get. As noted on the final APNIC request:
APNIC reiterates that IPv6 is the only means available for the sustained ongoing growth of the Internet, and urges all Members of the Internet industry to move quickly towards its deployment.
The deployment of IPv4 addresses will continue in each region until they are individually exhausted. It is likely that either APNIC or ARIN will be exhausted in advance of others (such as AfriNIC or LACNIC). Some may exhaust their pools as soon as the end of this year; others may survive into next year.
To help accelerate the adoption of IPv6, Google and others have proposed World IPv6 day on 8th June 2011; you can test your IPv6 connectivity in advance. The transition to IPv6 will involve hosts dual-hosting sites over both IPv4 and IPv6; it is fairly likely that the IPv4 internet will continue for some time to come. For example, if you have a blog hosted on blogger, then you can make it available make it available over IPv4 and IPv6 for consumers over both networks.
Have you prepared for IPv6? Does your ISP natively support it, or have you configured a free IPv6 tunnel from Hurricane Electric or Sixxs?