We study a possibility to define the (braided) comultiplication for the
GLq(N)-covariant differential complexes on some quantum spaces. We discover
such `differential bialgebras' (and Hopf algebras) on the bosonic and fermionic
quantum hyperplanes (with additive coproduct) and on the braided matrix algebra
BMq(N) with both multiplicative and additive coproducts. The latter case is
related (for N=2) to the q-Minkowski space and q-Poincare algebra.Comment: 7 page