If you are looking for a ready to use solution to access Amazon webservices within PHP you might look at PHP-AWS, a collection of PHP library that lets you take advantage of Amazon's web services platform (AWS). Currently, there are classes for use with:

• Simple Storage Service (S3)
• Simple Queue Service (SQS)
• Elastic Compute Cloud (EC2)
• Mechanical Turk (MTurk)

The project is released under MIT License, there is no download package yet of the project but you can get class sources separately from PHP-AWS SVN.