The NYT, Guardian and Der Spiegel were leaked the reports several weeks ago. Each has spent the past month analyzing the reports and writing articles with their key deductions. According to the New York Times editors' note:
The articles published today are based on thousands of United States military incident and intelligence reports — records of engagements, mishaps, intelligence on enemy activity and other events from the war in Afghanistan — that were made public on Sunday on the Internet. The New York Times, The Guardian newspaper in London, and the German magazine Der Spiegel were given access to the material several weeks ago. These reports are used by desk officers in the Pentagon and troops in the field when they make operational plans and prepare briefings on the situation in the war zone. Most of the reports are routine, even mundane, but many add insights, texture and context to a war that has been waged for nearly nine years.The NYT, Guardian and Der Spiegel have all vetted the reports and come to the conclusion that the material is authentic.
You can download the full set of reports from the WikiLeaks website, here.
New York Times coverage is found here.
Guardian coverage here.
Der Spiegel coverage here.