In the first official U.S. comment about Area 51, the CIA has finally acknowledged the base in a newly declassified version of its history of the U-2.
The entire document is available as a pdf at the National Security Archives website:
This history was originally declassified in 1998 but with many redactions (deletions). This new version removes most, but not all, of these edits. Some of the new material is not surprising or has been covered in open sources elsewhere, such as the role of RAF (2 overflights of the USSR in 1959).
Noted author and U-2 expert Chris Pocock provides an exceptionally valuable page-by-page summary of the new material.