A link to this was posted to slashdot this morning. It’s a pretty interesting/entertaining map to read. It shows allocations of IP addresses across the IPv4 internet with unallocated blocks illustrated as grassy areas. For example, this server’s address (188.8.131.52) is in the “U.S.A” block, because it begins with a “66”.
When I moused over the image, it says, “For the IPv6 map just imagine the XP default desktop picture.” Which interpreted, means that much of the IPv6 address space is currently unclaimed.
On a more technical note, IPv4 uses 32 bit addresses, IPv6 uses 128 bit addresses. Here is an example of what each looks like, IPv4 – 192.168.1.101 (that address should probably look familiar), IPv6 – 30ac:0db8:85a3:08d3:1319:8a2e:0370:7334 (this looks scary to me!) The IPv4 address space contains 4,294,967,296 addresses but the IPv6 contains 340,282,366,920,938,463,463,374,607,431,768,211,456.