For those attended my session LEVERAGING SHAREPOINT IN A SOA-BASED INFRASTRUCTURE the slides and solutions can be found here. NOTE: You will need to click on the download link once you are on the page.
For the gentleman that had the question about securing calls between the BDC and the sample web service, please read this article for how to pass credentials from the BDC to a web service using SOAP Headers. As for how to allow for SOAP headers in a WCF based service see the following reference. I may have originally misunderstood the context of the question that you asked in that I thought you were just asking how to secure the call between the BDC and the web service but the way the conversation went it sounded like you may have been asking a more general question of how to secure web services. I would be happy to provide recommendations on how to secure web services if you would like to chat. Either way please feel free to contact me if you have any questions.
Thank you to those of you who attended and let me know how you liked the material.