They're not infected with spyware. Some of the computing power comes from the users of freeware applications, who are asked _during install_ if they want to enable the grid system that powers us.
The article I read was about one of these freeware applications (something starting with "G", and a green Logo or mascot I think, I can not remember unfortunately), which installs the spyware if the users does "Express Install". Buried in the TOS is "we may use your computing power". It was by a third company, which in turn is supposed to be used by 80legs. Perhaps 80legs is not even aware of the shady practices of that company.
You're talking about Digsby. If you managed to follow the story to its conclusion, you'll see that they dramatically changed the install process to follow Plura's (our sister company) affiliate agreement.
Have you thought about the economics of having a program where people earn money from allowing use of there processing power vs paying for it regularly/ having your own processing power.
Even if it was barely worth it for the user after factoring in electricity costs the novelty factor might attract people.
