I completely overhauled my entire site, including the home page about 3 weeks ago. I also picked up a few links from high pr sites. The site is a pr4, but has climbed steadily over the past 3 weeks for my most important keywords. I believe it is not only do to the high pr sites, but the reciprocal link exchange program i began about 3 months ago. Before this time, the site could not be found in the SERPS at all. Now it is # 50 out of over 17,000,000 results for my most important and competitive keyword. It is climbing by leaps and bounds and has climbed more than 60 places over the past 3 weeks.