A plain hub doesn't have its own MAC address because it doesn't have any network identity per se -- it is just passing packets around.
But any managed hub -- or the gateway/router/hubs that Linksys and other sells -- do have their own MAC address because they have some kind of network identity to them. The Managed hub port typically has a special network interface that can be connected to via an SNMP manager like OpenView or Unicenter. The Linksys and other router/hubs have a network interface that is managed with a web browser, although some managed hubs also can be managed with a Web browser, as well.
This was first published in February 2002