A survey on separators?
Not exactly the most recent (published in 2001), but the text by Arnold L. Rosenberg, Lenwood S. Heath, "Graph Separators, with Applications" may be a good place to look. The Google book link is provided here:
http://books.google.ca/books/about/Graph_Separators_with_Applications.html?id=7DNKE5ZiNZYC&amp;redir_esc=y