Contractors can work simultaneously on different projects for different teams, irrespective of the geographical locations of their various employers. If it was really that one-sided, we'd all be doing it. In truth, virtual teamworking is only possible for those in the knowledge-based industries, particularly those on the technical side of IT and networking. Here, virtual working technologies are all-pervasive and many workers are quite happy sitting in front of a screen all day, with only email and IRC chat to keep them company. Even then, many employees still prefer to work in an office.
Virtual teams present other significant challenges.
If you just pull a few people together for a project you can't always guarantee the quality. We do employ contractors on occasion, but it's much better if you have a core of people you can call on. It is becoming easier for organisations to put together virtual teams of contractors for specific projects while retaining control over the quality of those workers. Companies such as Elance and Smarterwork are already acting as online agencies for virtual workers, providing additional services including vetting the skills of those offering their services. We also list all their credentials - and have rigorous systems to check those are genuine.