The home page for Amazon Web Services (AWS) is www.amazon.com/gp/browse.html?node=3435361. From that page, you can register for an ID, download and read documentation (including code examples in a variety of languages) and participate in forums for AWS developers. A frequently updated Weblog with news and ideas about AWS is at aws.typepad.com.
All of Amazon's Web services can be accessed using either SOAP or REST. An overall introduction to SOAP, including XML examples, is at www.intertwingly.net/stories/2002/03/16/aGentleIntroductionToSoap.html.
An established Perl library for SOAP, known as SOAP::Lite, is available from CPAN and described (with extensive documentation) at www.soaplite.com. A similar tutorial for using SOAP from Python is at www.diveintopython.org/soap_web_services.