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When you ask a question here, we volunteers need to take a look at your blog—to be sure you are in the right place or to see what is wrong. Please always provide a link to the blog you are asking about, starting with http://
Wordpress.com sends pings when you make a new post. But updating a post will not cause a ping. That means search engines and sites like Technorati, Feedster, Icerocket, Google Blog Search are not repeated notified of the post. You won't be seen as a spammer.
One way to edit a post and check how it looks repeatedly is to publish the post privately, then when you are satisfied, make it public. People looking at your feed will then see the version of the post you want them to see.