See also Stack.
An excellent introduction to derived AG is the CRM 2008 notes, in Toen web unpublished folder. These notes also covers algebraic stacks, the idea of moduli spaces, a little about cotangent complexes, and examples of derived algebraic stacks.
http://mathoverflow.net/questions/73115/query-on-comment-in-deligne-mumford-1969
nLab page on Algebraic stack