What attracts search engines is unique content the cannot be found anywhere else on the internet. Keep publishing original content frequently because it can take weeks before indexing will happen.
The process we use for verifying free hosted WordPress.com blogs with search engines is found here > http://en.support.wordpress.com/webmaster-tools/
Note: Even if you do not verify the blog the content will be indexed by search engines so don't feel panicky about this please.
WordPress.com provides the search engines with site maps. We bloggers do nothing. http://en.support.wordpress.com/sitemaps/
For more information read > http://onecoolsitebloggingtips.com/2010/01/21/omg-i-cant-find-my-blog-on-google/