Update: This story was reported earlier, in greater depth (and in English!) by the Guardian . Thanks to Damian Carrington.
Material that the French newspaper Le Monde has harvested from Wikileaks documents show that American diplomats were aware as early as the summer of 2009 that hackers were trying to break into climate scientists' computers, Carrie La Seur of the Plains Justice environmental law center reports on her blog. 
La Seur reports: "An article posted Dec. 12, titled Pirates informatiques contre climatologues  (Computer pirates against climatologists), reveals a few American diplomats’ fears that cyberattacks on climate scientists might increase in the days leading up to the 2009 Copenhagen meeting. One email reveals an unsuccessful attack against the U.S. State Department’s Bureau of Oceans, Environment and Science  (OES) that has received very little coverage (none that I can find) in domestic press."