On the Friday of Memorial Day weekend, Google release it's first update to the new anti-spam and quality control system called Penguin. Like Panda, Google Penguin is focused on improving the quality of search results by reducing the rank of low quality and spammy websites and web pages.
Penguin 1.1 was release this past Friday and Google calls this update a “data refresh,” which will impact a little less than one-tenth of a percent of English-language searches. For some webmasters, this 0.1% of English-language searches could mean a lot or a little--depending on what kind of websites you own and whether they are targeted. Additionally, some websites may drop in rank, not because they were directly targeted, but because websites with supporting backlinks may have been affected--causing a chain reaction within some networks.