It's probably not important to them, as I'm not their target audience but I looked at their home page and their about page and that techcrunch article and still have no idea what they do.
If a web app had a secure API to include all of my class lists automatically, I'd be much more likely to use it.
Ours is ugly but functional.
edit: Apparently I misunderstood what I read. Sorry.
Clever actually isn't an SIS, though--we provide an API/integration layer that sits on top of the SIS.
We think SISes are great at a lot of things (state reporting, for example). Providing a nice interface for developers is not one of those things.