Tom C has posted a great article about Penalties from Google.

* Do I have a penalty?
* Why do I have a penalty?
* How can I get rid of my penalty?

Unfortunately, they’re elusive to tie down. Since you get penalties (generally) for doing something wrong in Google’s eyes, they’re not very forthcoming about what they do to you when they catch you. If they had their way, I’m sure they’d like to just say BAD STUFF in their guidelines. As it is, however, penalties typically fall into a couple of distinct categories and Rand has a flowchart for determining whether you have a penalty or not. This flowchart has historically worked very well and covers the vast majority of penalties (thanks Rand!).

Read the full article