Danny Sullivan of Search Engine Land is holding his SMX conference in Sydney right now. Turns out Danny had a keynote with Google’s Marissa Mayer and was able to get some interesting information out of her about a new search feature called “previous query.”

Previous query is a concept that is already implemented in Google’s paid search results. Basically what this functionality does is looks at the previous query made and will display different ad results based on the combination of the two queries. So let’s say you did a search for the word “Munich” and then did a new search for the word “car rental.” Using the previous query functionality, Google would modify their paid results to reflect a search that more closely resembles “Munich car rental.”

In their talk, Marissa told Danny that users can expect to see organic search results that use previous search style search behavior. In my mind announcement wouldn’t be a big deal, except for this – users will not need to be signed into a Google account to see the previous search functionality – previous search is cookie based, so as long as your browser accepts cookies, you’re going to be affected.

From an SEO standpoint, this could be big – especially if you rely on people doing one word queries to find your site. As Danny points out in his post, this will make many “single word” queries bring back queries of two or more words, depending on your previous search.

What should you do to optimize for this change? From what I can tell, nothing really. Based off the search results shifting I’ve seen on Google as of late, it’s getting harder and harder to safely say what you rank for a particular keyword – and the addition of previous query will only make your actual positioning on Google that much more subjective.

If there is any advice I would give it would be that its really time to make sure you have a good grasp on non-ranking related metrics to evaluate your SEO success. Look at visits, pageviews, leads, sales, whatever – just don’t rely on search rankings alone – chances are they’re not going to be the same for everyone.

Check out Danny's post about the keynote here.