Every since the proliferation of broadband connections (cable and DSL) to the Net started booming, the fate of IPv4 has been numbered. Every computer that connects directly to the Internet has to have a unique public IP address. And they are running out of numbers.

In the days when connections were primarily dialup, it wasn't as big an issue. Only a fraction of an ISPs subscribers were online at any time, so they could get by with a smaller number of IPs. But broadband users tend to stay connected 24/7 so they have a quasi-static address. This means the ISP needs to provide an IP for each subscriber.

IPv6 has been in development for a while, but I think the problem is implementing it. It's a similar situation to switch over to all digital TV scheduled for February.

I would hope ISPs will inform their subscribers how the switch will affect them. It may mean replacing broadband modems and/or routers. I don't think it will mean replacing Ethernet adapters, though. But I do think people with a subscription need to be aware.

Finally to clarify, this doesn't affect computers on your LAN. Generally your router provides a PRIVATE IP address (usually in the 192.168.x.x range). So, for example, you can have a PC with 192.168.1.2 and your naeighbor can have a PC on their LAN with the same IP. But you will each have a different PUBLIC address assigned to your broadband modem. So you can add as many as 255 devices to your LAN without using up the Private addresses.

IPv6 isn't needed yet at all. As a matter of fact, it even causes connection problems with Vista. Keep it turned off if you want to surf at full speed and constant connection.