Here are a couple links you can read up on the problem. On 8 June, 2011, IPv6 will take a test flight on what has been designated World IPv6 Day.

Google, Facebook, Yahoo, and others will offer their content over IPv6 for a 24-hour trial run with the goal of shedding an early light on potential glitches and ensuring a smooth transition to IPv6.

The transition to a new protocol that will support a virtually unlimited number of devices on the Internet is currently underway. Whereas IPv4 uses 32 bits for each IP address and can support 4,294,967,296 addresses, IPv6 uses 128-bit addresses to support approximately 340 undecillion unique number sequences (that’s 340 with 36 zeroes after it).