Hi, I'm the author of Riemann. This part of the documentation is aimed at people who already know what Riemann is, so your confusion is completely understandable! :)

In short, Riemann is a complex event processor, driven by Clojure configuration, oriented towards monitoring distributed software systems. There's an introduction to its features and concepts here:

http://aphyr.github.com/riemann/

You can watch me try to justify my crimes against computers here:

http://vimeo.com/38377415

And here's some slides!

http://t.co/9BKdufal

If there's any questions I can answer, happy to help. You're also welcome to stop by #riemann on freenode. Cheers!