Michael Silberman over at EchoDitto makes some great points on why this is big:
This investment is a Big Deal because it speaks volumes about the company's appreciation for (a) the online multiplier effect, where many small, individual actions add up to a larger whole, and (b) the proven nature of distributed and decentralized processing via the 'net.Basically, Amazon has created a tool that enables you to export your simpler (but more challenging) tasks to an army of willing workers online. Using this new API you can submit requests and tasks to the Amazon Turk website, approve completed tasks, and then incorporate those solutions into your own software. On the other end, humans can select HITs (Human Intelligence Tasks) to complete. You get paid once the person who listed the HIT approves your solution or work. So in a sense this is what happens when open-source idealogy mixes into the online job market.
For businesses and entrepreneurs who want tasks completed, the Amazon Mechanical Turk web service solves the problem of getting work done in a cost-effective manner by people who have the skill to do the work. It does this by ccessing a vast network of human intelligence with the efficiencies and cost- ffectiveness of computers. Oftentimes people do not move forward with certain projects because the cost to establish a network of skilled people to do the work outweighs the value of completing it. By turning the fixed costs into variable costs that scale with their needs, the Amazon Mechanical Turk web service eliminates this barrier and allows projects to be completed that before were not economical...For people who want to earn money in their spare time, the Amazon Mechanical Turk website solves the problem of finding work that they can do wherever and whenever they want.
But don't get too excited. At the moment you'd be hard pressed to find a gig for more a few bucks. You'd still have to file for unemployment if you took this on full time.