I have a technology blog that recently jumped for PR3 to PR4 and has been around for more than 2 years. The site gets visited by the Googlebot often enough. New posts are generally indexed within minutes and an XML sitemap is in place. I am running into a problem, however, where a new post will get decent placement on Google, but after it falls off the first page, loses its rank. This post is a good example: http://www.pcfastlane.com/reviews/relakks-the-key-to-anonymous-surfing/ It used to rank well for Relakks-related search terms, but has dropped to page 5 for the term "Relakks". Additionally, Google has a bad habit of indexing my main site instead of blog posts. This only occurs with new posts on the first page. Look at this new article: http://www.pcfastlane.com/features/the-sonicare-toothbrush/ When I Googled sonicare toothbrush the post above used to appear, but if you go to the third page of results, it shows my website homepage. This problem is ongoing with this post as well as others. If anyone could help me fix these SEO isses, I would be very grateful.
Set up a robots.txt file - I had this problem once until I literally wrote a plain robots.txt file and dropped it in. If you're using a robots.txt plugin, get rid of it.