I've been saying for a few years now that the future of home computing is in networking.
I would not be a bit surprised to see, in the next few years, computer clusters being commonplace in homes, allowing people to leverage the super-computer power from their home network, while interfacing from an energy efficient laptop, or even smart phone-like device.
Since most computers typically use far less than their maximum available processing power, it makes sense to allow load balancing among the computers on the network. This idea could be extended to external networks, such as the wireless network at the local coffee shop, or even specific LANs accessible via the WAN, whether that network is located next door, or across the globe.
Essentially the idea is to efficiently utilize available CPU power in the same manner that bandwidth is utilized efficiently with bittorrent. Projects like Folding@home and SETI@home do such CPU sharing on a large scale. Implementing the same idea on a LAN would allow tasks best suited for powerful computers, such as those powered by multiple processors, each with multiple cores, to be completed in a timely manner by much less powerful, yet far more common computers that exist on the same LAN. Thus, CPU power would be available when needed, but without the need to purchase high end computers.
Mac OS X v.4 and later include Xgrid, which allows "easy" implementation of distributed computing with networked Macs. Unfortunately, Apple does not provide a GUI controller for Xgrid in the standard client OS X install, so it requires use of the command line. (Apple provides a GUI as part of Server Admin Tools, a free standalone download. Xgrid@Stanford also offers such a GUI, called
GridStuffer.) I'm not sure whether Microsoft offers a similar tool to allow networked computers to easily engage in distributed computing, nor do I know if such a tool is readily available for Linux or other *nix operating systems.
Another stumbling block is application compatibility. For example, I use handbrake for most of my video format conversions, but I'm not sure that Handbrake currently supports such task distribution.
Still, I don't think it will be long before home networked (or even ad-hoc networked) grid computing will be extremely easy and widely available and utilized. I can even envision being able to buy clusters in the same manner and similar form factor as servers are currently available. That is, instead of multiple processors for the same computer in one case, there would be multiple single processor computers in the same case, which could be used independently or together, or some combination thereof, depending on the users needs at a particular time.