What are spinners?

Tools and systems that take a corpus of root text and create large number of variations of that content, to avoid duplicate content penalties when trying to stuff sites to catch Google's attention.

Or, as a a "spinning" script might reword it:

> Implements and setups that take a corpus of tuber text and create meaty number of changes of that tranquil, to avoid duplicate content sanctions when trying to stuff localities to catch Google's contemplation.

Like serkey.com? God I hate that site; it came up with most of the front page for pretty much every Oracle related query lately. That it until these changes, apparently.

Well done Google!

Please explain article rewriting.

EDIT: That was my #fail at answering the question with spun text. Duskwuff did it well!