Google filing says Gmail users have no expectation of privacy(news.cnet.com)

  Plaintiffs in the case contend that Google's automated
  scanning of e-mail represents an illegal interception of
  their electronic communications without their consent. 
  However, Google, which uses automated scanning to filter 
  spam and deliver targeted advertising to its users, noted 
  that plaintiffs consented to the practice in exchange for 
  the e-mail services. Google goes on to say that courts have 
  held that all e-mail users "necessarily give implied consent 
  to the automated processing of their emails."