I think, before too long, RSS feeds aggregated like this will be common practice. Users are all familiar with email, and placing the aggregator in a message-based context actually provides new functionality for content providers too – they can save bandwidth by letting people pull in the new content they’re interested in reading, and better yet, correct mistakes. When you send out a mailing list to subscribers, there’s no going back – with an RSS feed you simply change the content and wait for the clients to reload.
Within an educational context, this means that central information – like course notes, perhaps a lecturer’s blog – can be stored in one place but broadcast to their students. No worries about incorrect email addresses; just a single point of failure. I’d be interested to hear about anyone’s experiences doing this, with Elgg or any other software.