Google make around 500 changes to its search system each year; some are minor changes, but some have huge impacts on your sites’ search position.
Possibly one of the most important changes is a focus on fresh content; something that has been featured in the Official Google Blog;
As we announced just over a week ago, we’ve made a significant improvement to how we rank fresh content. This change impacts roughly 35 percent of total searches (around 6-10% of search results to a noticeable degree) and better determines the appropriate level of freshness for a given query.
There’s also changes to how duplicated boilerplate text is dealt with – something that should generally always be avoided.
While these changes are useful to note; there is no reason to make drastic changes to your site; these announcements should be taken as an indicator to improve and optimise especially where it can be a easy task and a quick win; and especially where it helps your visitors too.
The entire list can be found on Google’s Inside Search Blog