It's an IPv4 world today, but the days of IPv4 are numbered.
As of February 2011, the Internet Assigned Numbers Authority (IANA) had allocated all remaining public IP address ranges to the five global regional Internet registries. A quick look at this IPv4 Exhaustion Counter below shows a total of 13.24 /8 (8-bit) IPv4 address ranges remaining, for a total of less than 3,400 remaining unallocated IPv4 addresses. Essentially, this means
IPv4 is played out.
In this sponsored brief by Ed Tittel and Jeff Carrell, you can dive into the basics of IPv6 and start planning your network's transition.
How to Prepare for IPv6 Networking explains the benefits of IPv6 (it's not just more addresses), what's needed to support IPv6 and a case study for IPv6 setup. If you're not acquainted with IPv6 yet, it's time to get started.