340,282,366,920,938,463,463,374,607,431,768,211,456

Ars Technica has a great article on IPv6 (via Slashdot):

As of January 1, 2007, 2.4 billion of those [IPv4 addresses] were in (some kind of) use. 1.3 billion were still available and about 170 million new addresses are given out each year. So at this rate, 7.5 years from now, we'll be clean out of IP addresses; faster if the number of addresses used per year goes up. Are you ready for IPv6?

If you're not in a geek reading mood, this post's title expresses the number of addresses IPv6 will allow for. C'mon, try and pronounce it! :)