So there has been a fair bit of talk in the SEO community about the so called Google Farmer / Panda update and its effects. The idea with this update was to reduce webspam in the results, specifically those shallow informational articles (shallow How To's as so forth) that used to appear are now getting pushed down the listings thankfully. It was also targetting content farms (hence the "Farmer" label applied to the udpate) which basically are sites more intended for search engines than actual humans, which probably sell links or banner ads to make money, rather than have an actual product.
Personally, I think I like the change. I've been doing some searches for informational How To subjects and have been finding some excellent articles in high positions that really do answer my question. All of the sites I look after have seen an improvement in organic traffic from Google - see the screenshots from analytics below covering the period this was supposed to have rolled out. It should be noted that most of these sites have very clean white-hat link profiles, so go figure.
Google actually makes about 200 algo changes per year so this all needs to be taken in context, however Google themselves said this affects like 11% of the resutls which is humongous.