It sounds like a new book might need to be added to the list of must-have Ruby books: “Enterprise Integration with Ruby”, written by Maik Schmidt and published as a Pragmatic Bookshelf title, is currently in beta. As with all Pragmatic Bookshelf titles, you can purchase the beta PDF now and receive the full PDF or paper version of the book as soon as it comes out.
The book covers a diverse range of integration topics, including databases, LDAP, XML, low level services like sockets, HTTP, and REST, high level services like XML-RPC and SOAP, and more.