Sean McGrath raises the fuzzy boundary between content and presentation. My thoughts on the matter...
The concern about content vs. presentation is based in code maintenance. The model-view-controller design allows the model and the view to change independently (controller has remained a bit of a bear).
This separation is less of a concern on the web, although adapting content to multiple presentations is more than desirable. For example, "micro-formats" that embed content within HTML (which is perhaps 'semi-presentational'?) such that CSS can style based on more content-specific content than HTML itself, and such that automated systems can ignore the presentation and drive actions based on the content.
Supposedly the automated systems should care less if the presentation aspects of the format changes and vice versa. Agile data formats and processors should have less to do with a content/presentation dichotomy, and have more to do with semi-structured data, i.e. whether or not the document has enough information of the expected kind to do useful work.