What is the Message?

I’m doing two subjects at uni at the moment, one is Technocultures and one is Introduction to Media and Popular Cultures, so I’m mainly thinking about media related things at the moment. Next week as part of a tutorial I have to give a presentation on someone’s interpretation of McLuhan’s theory that “the medium is the message.” Whilst I was thinking about this I read part of this article, which made a comment about current media:

Today’s media is in fact much closer to a real-world ecosystem in the way it circulates information than it is like the old industrial, top-down models of mass media. It’s a much more diverse and interconnected world, a system of flows and feeds – completely different from an assembly line.

It made me wonder, if the medium is the message, then what is the computer’s medium. Is it the screen and keyboard? Is it the application? If it’s the application, then does that mean that the content you get from an RSS reader is different from the content you read in the web browser?