According to Geoff Huston, Chief Scientist of the Asia Pacific Network Information Centre (APNIC), the internet is going to run out of available IP addresses much faster than most people (incl. ISPs) realise.
The underlying protocol, IPv4 has a limit of about 4 Billion IP addresses. However, due to everything from computers to mobile phones to the latest high-tech refridgerators and air conditioners snapping up an IP address, the boundary is being neared with only about 232 million addresses left. Geoff Huston says he has worked out all the figures and at the rate of addresses being taken up, IPv4 address availability will reach the end of the line in about 340 days.
The answer? IPv6 which is capable of providing trillions of addresses for every person on the planet. However, ISPs and websites have been reluctant to move over to the new protocol as all devices connecting via that protocol would need to be either reconfigured or upgraded with new firmware, or in some cases, replaced altogether.