During October Google has made considerably more large algorithm updates:
This update targets sites with too many ads above the fold. Google have made this update due to complaints of users coming to sites and not finding the content they are looking for quickly enough, as they are mainly seeing Ads instead. This of course negatively affects the user experience which Google is always trying hard to improve (although Google, can you please work on improving the user experience of the AdWords management interface?) The first 'Top Heavy' update was on 19 January, 2012. Source: Google's Matt Cutts on Twitter, and Search Engine Land
The penguin update is a spam-fighting algorithm and the 3rd so far, the first going back to April 24 this year. This latest Penguin update is only expected to affect 0.3% of search queries, compared to the first one which affected around 3.1%. Please note that on Twitter Matt Cutts has advised the 0.3% is what is noticeable, and this may only apply to the top 5 results on Google's first page. I.e. above the fold. So what does this update mainly target? Primarily web spam. Search Engine Land also believes this is primarily focusing on too many poor quality inbound links. The first 'Penguin' update was on 24th April, 2012. It's important to make sure your company's SEO strategy has allowance for these changes, and of course your SEO specialist is keeping up-to-date with them.