There is a distinct need to have website interaction in regards to Dynamics CRM 2011, ive added a solution to my projects area that deals with authentication of a open source CMS agaisnt a contact record in dynamics CRM.
I have also attached the solution as a download for you to get a idea on how to tackle this type of requirement.
The solution involveds php encrypted soap messaging to dynamics crm 2011.
I hope you make use of it.
The article can be found here.
Enjoy
Jonathan