In a CNET Interview, Bill Gates says that everyone needs a "home server":
If you have got multiple PCs than you want files that are available all the time no matter which PCs are turned on or off and you'd also like to have a server that when you just add just add storage it automatically takes advantage of that. You don't have to think about drive names or moving files around.
The need for this is real but the suggested implementation is flawed. What we need is a cheap network attached disk appliance. This device would be plugged into your home ethernet router, and then accessed wirelessly by every machine in your house. Standard protocols would be supported so that other devices could discover and use the space - for example a Tivo, a wireless camera, an Apple iTV, etc...
Serving disk space doesn't require a full blown server, especially not one running a copy of Windows as I'm sure Gates was implying. For years, companies like EMC and NetApp have supplied network attached storage for businesses. It's time for these systems to trickle down to home users. A few devices, including one affectionately called "the slug" are available for the home but they're still a bit too expensive ($50-100 plus the disk) and hard to use for the average person. Once someone figures out the right packaging, price, and ease-of-use, these devices could really take off.
Gates didn't even mention this, but in addition to disk space, homes need network attached printers as well. These printers are available today for a small premium from companies like HP. While you could attach a printer to a shared file server, why bother? A separate device for each shared service (disk and print) will be simpler and interchangeable.