I think Matt hit on a couple of key things on this subject that easily translate in to our current experiences with the Panda update. Using words like “trust” and “user experience” tell me that while it may not be a direct ranking signal…. It is being signaled from other relevant areas such as we see in the quality guidelines Google has given us in regards to Panda.
Normally, I would not blog this, as I am a fervent believer in the “PageRank is not a big deal” mentality. You see, I put little if any stock in that little green bar, and instruct our clients likewise. We rather belong to the “build it and they will come” theory of SEO. In part our belief is that natural links, on page optimization, fresh content, elimination of duplication and unique text are in fact the key to organic search success.
Blocking my page in robots.txt will prevent indexing.. This is just not true, your robots.txt is a tool used to prevent crawling… not indexing. While blocking a page in robots.txt will prevent well behaved spiders from crawling these pages, it will not prevent indexing, remove a page from the index, nor block the flow of PageRank to the page.
You may be wondering how search engines select the top pages from millions of others. There are calculations involved called algorithms and you have to work with these to put your site in page one. The great part is that all of the things search engines look for to rank your site are beneficial to your shoppers as well.