It is proved that Kaygun's Hopf-Hochschild cochain complex for a module-algebra is a brace algebra with multiplication. As a result, an analogue of Deligne's Conjecture holds for module-algebras, and the Hopf-Hochschild cohomology of a module-algebra has a Gerstenhaber algebra structure.
Homology, Homotopy and Applications, Vol. 13 (2011), No. 1, pp.259-272.
Available as: dvi dvi.gz ps ps.gz pdf