As I have understand WordPress 4.0.1 has it's own "Update Service" enabled by default. The address indicated in my case is http://rpc.pingomatic.com/. So based on this thing I can state that my WordPress pack has ping service implemented and enabled.
However there are several plugins that can automatically build and upload XML Sitemap to major search engines (Google, Bing, Yahoo...).
For me it looks like those plugins is not really necessary. But if I really need my posts to be quickly indexed and well ranked: do I need to consider any of those plugins to make my chances to gather traffic any better?