  This is a contribution to the ICM 2002. We explain the relation between the
(equivariant) Bloch-Kato conjecture for special values of L-functions and the
Main Conjecture of (non-abelian) Iwasawa theory. On the way we will discuss
briefly the case of Dirichlet characters in the abelian case. We will also
discuss how "twisting" in the non-abelian case would allow to reduce the
general conjecture to the case of number fields. This is one the main
motivations for a non-abelian Main Conjecture.
