http://www.dougdemercurio.com/share-this-wordpress-plugin If you Use and share this WordPress plugin, you will find all of your blogpost pages continue to be indexed by Google. If you don’t use and share this wordpress plugin, you will find that your older posts will start to disappear from the indexing. What this means is your blog will drop in ranking overall, and so will the ranking of all your posts because you wont have as many pages indexed on your domain.
So if you want to maintain your high rankings, I suggest that you use and share this wordpress plugin with your fellow bloggers. They will be very grateful to you.