This might have several different meanings.
arXiv: Experimental full text search
RT (Groups and representation theory)?, AG (Algebraic geometry)?
Check talk by Simpson in London.
CUP volume: Galois groups and fundamental groups (2003)
Serre: Galois cohomology
Some papers of Breen, see MathSciNet.
Book of Giraud, see Giraud folder, or maybe moved to AG
nLab. See also nonabelian cosheaf homotopy and nonabelian sheaf cohomology and nonabelian cocycle
Toen: Stacks and nonabelian cohomology, MSRI talk 2002, in Toen folder.
http://mathoverflow.net/questions/36466/do-we-have-non-abelian-sheaf-cohomology
http://mathoverflow.net/questions/2390/why-does-non-abelian-group-cohomology-exist
nLab page on Nonabelian cohomology