We argue that several materials of much current interest in condensed matter
physics share common phenomenological aspects that only very recent
investigations are unveiling. The list includes colossal magnetoresistance
manganites, high temperature superconducting cuprates, diluted magnetic
semiconductors, and others. The common aspect is the relevance of intrinsic
inhomogeneities in the form of "clustered states", as explained in the text.Comment: elsart3, 6 pages, 5 figures. Invited paper for the Conference
Proceedings of the International Conference on Magnetism, Rome, July 200