The World Wide Web is evolving into a medium that will soon make it possible for conceiving and implementing situation-aware services. A situation-aware or situated web application is one that renders the user with an experience (content, interaction and presentation) that is so tailored to his/her current situation. This requires the facts and opinions regarding the context to be communicated to the server by means of a profile, which is then applied against the description of the application objects at the server in order to generate the required experience. This paper discusses a profiles view of the situated web architecture and analyzes the key technologies and capabilities that enable them. We conclude that trusted frameworks wherein rich vocabularies describing users and their context, applications and documents, along with rules for processing them, are critical elements of such architectures.