If its say a 2950 layer 2 switch, you would assign an IP address to enable remote access via telnet.This IP address isn't being assigned to a physical interface, its assigned to a logical interface Vlan 1(i.e. no physical port is attached to vlan 1). Vlan 1 is what is known as the management vlan.
Hope that helps, if your taking CCNA I would read up on this area :-)
If you want to have a routed uplink to/from another L3 switch or a router, that's a good way to do it. It's simpler than creating a vlan and putting the port into it. You could route a layer 2 switch with it also. It simply gives you a routed link to whatever.