Thomas Dalton wrote:
This doesn't help ID the person (MAC tells you manufacturer, and sometimes model, but that's all). But it does help for blocking...
It helps to confirm that two people are the same. While a checkuser that shows that two accounts are being used by people with the same ISP would at best be a "likely", a checkuser that shows two accounts are being accessed via the same network card would be a definite match (assuming the rest of the address rules out a public computer).
However, see RFC 3041, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6". If this is widely adopted, it will render MAC address blocking pointless.
-- Neil