Even though I helped work on the Shibboleth module, I had never actually seen it running before.
Now I've seen Shibboleth in action I can really see the potential: it's very cool ... I think we'll start seeing this new capability in Moodle being used for a lot of exciting things.
If you know nothing about this, Shibboleth allows a secure single-sign-on across all sorts of sites (which now includes Moodle). We could technically open up all our Moodle sites to each other and allow authenticated users from one site to access any other.
In reality it'll mostly be used to allow access between smaller groups of institutions, but I'm starting to think about some sort of shibboleth.moodle.org for casual use.