  Let X be a compact almost complex manifold with an action of a finite group
G. We compute the algebra of G^n coinvariants of the stringy cohomology
(math.AG/0104207) of X^n with an action of a wreath product of G. We show that
it is isomorphic to the algebra A{S_n} defined by Lehn and Sorger
(math.AG/0012166) where we set A to be the orbifold cohomology of [X/G]. As a
consequence, we verify a special case of Ruan's cohomological hyper-kaehler
conjecture (math.AG/0201123).
