Amazon (s AMZN) Web Services (AWS) today launched its fourth annual startup-challenge, a contest that is open to startups that are using the Amazon platform in innovative ways. We have been following this contest since its inception in 2007, especially since it helps identify many of tomorrow’s star companies. Previous winners include Yieldex and Ooyala.

In an interview earlier this year, Amazon’s Chief Technology Officer, Werner Vogels said:

We are enabling a lot things in a way that will be long-term beneficial as it would help build more sustainable businesses using a lot less capital. The fact is that because of the cloud, today a young upstart can take market share without an incumbent having time to react.

In recognition of AWS’ growing international footprint, the company is going to pick regional winners in the Americas, Asia Pacific and Europe.

The Big Prize: $50,000 cash, $50,000 in AWS service credits, premium support services for one year, and a possible investment offer from Amazon.

Other Prizes: Regional semi-finalists will receive $2,500 in AWS service credits. Global finalists will receive $10,000 in AWS service credits and a trip to Palo Alto, CA., USA for the final judging and awards ceremony.  All qualified contestants will receive $25 in AWS service credits.

Rules and regulations: Check the AWS Startup Challenge Website