Illumio is an intriguing concept that allows you to easily tap into knowledge available in a specific social network or community. And even to make money from that knowledge if you're an expert yourself. But I do not see this as a stand-alone service, rather as something that should be added (where's the API?) to existing social networking services like MySpace, LinkedIn, etc. Each network has its own angle, Illumio is a great way of getting more value out of it.
"According to John Markoff, in the New York Times, Illumio - which runs under Windows - will make it simple to "pick the brains of friends and colleagues for opinions and expertise". The software links with Microsoft or Google desktop search engines indexes of users' hard drives. According to Markoff, it transparently distributes requests for information to the computers in a network of users. "The questions can then be answered locally based on a novel reverse auction system that Illumio uses to determine who the experts are."