I just found this paper in my school's library. Its not new and it looks like google + yahoo + msn have maybe given up on trying to find 'DUST' because they now let you do that

( http://googlewebmastercentral.blogspot.com/2009/02/specify-y... , http://ysearchblog.com/2009/02/12/fighting-duplication-addin... , http://blogs.msdn.com/webmaster/archive/2009/02/12/partnerin... )

Its still interesting that

1. Many sites have a lot of 'DUST'

2. It is not very hard to find the 'DUST'- which obviously reduces crawling time.