Google has incorporated a slight change in the webmaster guidelines:

Previously the webmaster guideline was: we strongly encourage you to pay very close attention to the “Quality Guidelines,” which outline some of the illicit practices that may lead to a site being removed entirely from the Google index. Once a site has been removed, it will no longer show up in results on Google.com or on any of Google’s partner sites.

After the change: we strongly encourage you to pay very close attention to the “Quality Guidelines,” which outline some of the illicit practices that may lead to a site being removed entirely from the Google index or otherwise penalized. If a site has been penalized, it may no longer show up in results on Google.com or on any of Google’s partner sites.

This implies that instead of stressing on a site being completely removed, Google says that it may be removed or penalized. On the surface this does not appear to be a big change. However, there could be a deeper meaning to it.