A client of mine has asked me to integrate a 3rd party API into their Rails app. The only problem is that the API uses SOAP. Ruby has basically dropped SOAP in favor of RE
Kent Sibilev from Datanoise had also ported the Rails ActionWebService library to Rails 2.1 (and above).
This allows you to expose your own Ruby-based SOAP services.
He even has a scaffold/test mode which allows you to test your services using a browser.