We often edit our own blog posts and make correction. Do you know that this may harm your blog.
When you publish a new post or you edit a post, WordPress automatically notifies to the pingomatic service.
Whenever you hit publish button of an existing post or page, wordpress inform the update service that new contents added to the post or page. Search Engines come and visit the updated page and find no additional content as such. So, search engines consider you as a ping spammer.
We faced similar problem for one of our popular site. When we discovered that we are marked as ping spammer, we immediately removed update service url. And after a month or so, we found the ban has been withdrawn. There after we never actually used any update service, however, we get search engines visit very frequently to our site and whenever we publish a post, it is listed in google search engine within a day.