Well, SETI@home and Distributed.net aren't quite what the gaming industry has in mind. Those are "high latency distributed systems" where it doesn't matter how long a task takes to be completed. They're wanting something more like a Beowolf cluster where each node (computer/console) is networked in high speed and the system can respond as if the processors were all in the same computer. The software is all custom to the node and it becomes difficult to add and drop units in real time. They're making lots of progress but it's still not rock solid.
Google actually uses a hybrid of the two distributed computing methods. They have successfully "cached the entire Internet" with a server room of thousands of individual disposable Linux boxes that work together to server pages and do searches. It's like the distributed.net model in that one computer works on a single task, but like a beowolf cluster because a central server makes sure the tasks are getting done in real time.
It's good stuff. I think the gaming industry is a good place to test bed the theory. Eventually when homes begin having 'home server' situations with several personal computers around the house, you'll see more of this sort of thing. Another good use for these methods of distributed computing is at large corporations. They have thousands of highend workstations that do nothing from 5pm to 8am, but they also own million-dollar number-crunching servers that do all the accounting and database munching at night. If someone could write a simple client application that made use of all those workstations (security and reliablity garounteed) they could save big businesses billions of dollars.
~LoudMusic