Why newspapers block Google

Newspapers are stopping their sites being indexed by Google in an effort to preserve their 'unique content'.

Yes, that's correct. They believe they have the monopoly on the facts they find & report and don't want the 'Big G' to find it, display it and link to them.

So why are they doing this? Well, they believe that a hyperlink from Google's news site isn't the same value as a user finding the content themselves..... http://thenoisychannel.com/2009/04/18/is-differentiated-content-enough-to-save-newspapers/

Note:
The arguement about what constitutes 'screen-scraping' and what is proper 'spidering & indexing' gets a little blurred here. But its not as if Google passes this information off as its own, instead it links to the newspaper site (albeit it does put up relevant paid adverts and make money from this)