What is specified complexity?

I've read several summaries of [William Dembski](https://en.wikipedia.org/wiki/William_A._Dembski) 's concept of [specified complexity](http://en.wikipedia.org/wiki/Specified_complexity) , including [one by Dembski himself](http://www.leaderu.com/offices/dembski/docs/bd-specified.html) , and I've got to confess I have no idea what he is talking about. Is it an attempt to prove God's existence mathematically?