DDG logs very litte information...so while NSA can subpoena DDG, there's no data to get.
Developers should read "Playing chicken with cat.jpg" [1] which was a response from cperciva [2] to the 37 Signals privacy blunder. It was discussed quite a bit on HN [3] and for me it was a perspective-changing read on privacy.
[1] http://www.daemonology.net/blog/2012-01-19-playing-chicken-w...