I just last weekend finished (for now..) wiring my house for ethernet. The attic now has the cable modem and WRouter, with cat5 lines going to all the rooms. The living room and bedroom have wired "HTPCs", the office has a dedicated file/print/backup server and 2 workstations on a switch, and there's a wireless laptop floating around (unless its in the office, where I plug it into the switch).
My fiancee doesn't understand why this needed to be done, but I figure that it will increase the value of the house when we decide to sell. I know that I would have preferred if we had bought a wired home - fishing the cat5 to all the rooms and setting up the jacks wasn't really hard, but it would have been nice if it was already done...