Google released latest update known as Panda, at 4:03 PM – 24 Jul (early in morning, EDT) which should affect ~1% of search results. I guess it’s enough to ruin a lot of blackhat SEO-ed websites. You can find more information here on how to improve your website – advice directly from Google:
New data refresh of Panda starts rolling out tonight. ~1% of search results change enough to notice. More context: http://goo.gl/huekf
I guess that more updates are incoming. Stay tuned.
Noticeable previous Panda updates:
Google Panda 3.8 (June 25th)