According to Wikipedia:
A pingback is one of three types of linkbacks, methods for Web authors to request notification when somebody links to one of their documents. This enables authors to keep track of who is linking to, or referring to their articles.
That means, you write a post and possibly use a link in reference to another post whether within your blog or to another blog – also known as an internal link or external link. Pinging your own links is not necessarily a bad thing unless your posts are already filled with spam, and linked to other posts with spam within in it. As already mentioned in my article Crossposting: Pros, Cons, and Etiquette, Google penalizes for spam, not penalizing internal linking or duplicate content, so Weblog Tools was not entirely according to Google’s policy changes. Though duplicate content and internal linking is not the same, the principle is. It also makes sense that this is okay as bloggers use some type of related post plugin for their blog, which links to 3 similar topics, not necessarily the one you may have internally linked within your blog.
Though pingbacks really do not deliver any content other than to notify that your post has been referenced either internally or externally as according to the WordPress Codex’s description of a pingback, it can be a great tool to help your readers learn more, especially when your site may contain valuable information that is of interest to anyone (ex – related posts plugin or internal link.)
Matt cuts talks about PageRank sculpting talks more about letting links flow, whether internally or externally. It is up to the webmaster to make some type of balance, meaning that you as the blogger will have to make sure to reference outside sources more (which is great for you and the person you are linking), while also linking internally to posts that are of similar interest and carrying on the topic so readers looking for more information will either stay or go to the sources that you are referencing. So, in using the Nofollow method within your own blog, you are basically saying that you do not vouch for your own posts, right? That does not sound like a confident blogger at all.
Do you use pingbacks? What are your views on using pingbacks?