Found this great article: http://bit.ly/q4iLiG. This helps show how to create the tag line for your book. Moonrat (I follow, on Twitter, but don’t know his/her name) gives great description on how to determine what your book is “about”.
I will be using this information for the work on my query I will post a little later this week. Stay tuned, but be sure to read the information at the link.