Is Plone search engine friendly?
Very much so. Plone automatically encourages search engine optimization best practices such as keyword-rich URLs, human-readable descriptions, and crawlable sitemaps. Many sites that switch to Plone immediately notice a jump in their search engine rankings, crawl quality and relevance.
As an example, plone.org is one of the few websites in the world that has a 9 out of 10 PageRank in Google, the same as major sites like those of IBM and Microsoft.