We currently don't offer a self-hosting option, unless it were in the context of an enterprise agreement. If this functionality interests you and you have a large volume of visits, please contact us and we can talk about specifics.

We were not aware of Shibboleth single sign-on before we launched, and someone noted the name collision on our Show HN thread. If many people are confused about this, we would certainly consider a different name. The development team wanted a non-generic name (e.g. CAPTCHA), and naming has proved a challenge for us, so if you have any suggestions, please let us know.