Have you heard about all these blank sites that are coming up in the Top 10? It's not because G actually likes these sites as they are now, it's because they used to like them. If you use the Wayback Machine from archive.org, you see these sites use to have content, often good content. Like with "Python hosting", the #1 is blank, it's been blank for years, but used to have content back in 2006. Normally if your site is down or blank, Google wastes little time is deranking you. But this Zombie update is bringing them back. They haven't totally reverted to an old index, or else newer sites wouldn't be there. But they are obviously rewarding sites for positions or content they used to have. They were forced to manually correct an old site ranking for "make money online" already. This was either an error, or they are planning on building on this with the next update, by pushing out sites with BH seo, bringing back old ones without BH seo, and rebuilding.