The blogs have only been around for a few days. It can take up to 6 weeks for the search engines to figure out exactly where to put your posts in search results, but typically it will happen with in a couple weeks. It just depends on how many requests are backed up at the search engines.
It can take a year or more before your blog will start appearing higher up in search results. It simply takes time.
As previously mentioned it can take up to 6 weeks for search engines to locate and index your blog. However, I’d like to draw your attention to this entry that provides instructions for getting a Google WebMasters account and registering your blog with the three major search engines. http://en.support.wordpress.com/webmaster-tools/