Slammed by Google Instant Search

I had a website that was ranking on the first page of google for a couple of keywords and then it just disappeared. My traffic dropped in half. My ranking on Yahoo went up however. Now I am starting to show up on the 4th and 5th pages of google again. Not sure what happened but it all started when google launched their instant search. I am sure all the basic on page SEO stuff is still going to apply but I am not sure how all the backlinking strategies are still going to apply. We will have to see. I am getting ready to try some Press Releases and maybe try SEOLinkVine.