The WordPress.com search engine indexes post, pages, and comments content (body text). Unless entered as text in those contents, blog name, post titles, and post/comment author names are not indexed.
WordPress.com automatically sends notifications to Google with every post and page update. The search engines can take 4-6 weeks or more to add any new sites. For more information about WordPress.com and Search Engines, please see http://support.wordpress.com/search-engines/ .
It will take a couple of days from the time you created your blog for to show up in WordPress.com search results. For more information please see http://support.wordpress.com/wordpresscom-search/ .
You can control whether or not search engines index your site in your Privacy Settings in your dashboard at Settings > Privacy Settings.
Please check out our support documentation at http://en.support.wordpress.com/settings/privacy-settings/ and let me know if you have any questions.