There was an interesting panel on Spec Work in regards to designers and the creative industry at the SXSW conference last week.
It is a very hot topic.
Spec work is neither good or evil. It's the motive behind it. Too often it's the buyer trying to get the cheapest price and is not considering the value added of a relationship. A good designer needs to understand the client in order to do their best work. I don't think the current model of spec work is a sustainable model as it does nothing to build relationships. It's oxymoronic to talk about "creative community" when these models destroy relationships and therefore community.