1. A method for arranging portlets in a Web Portal based on a hierarchical content structure of portal pages and portlets, comprising: retrieving data mining input data relating to said portlets; performing a data mining function on said data mining input data, resulting in a data mining result revealing respective similarities between said portlets, wherein the mining comprises clustering said portlets into a plurality of resulting clusters such that related ones of said portlets are clustered together; calculating a new hierarchical content structure from said data mining result, wherein said new hierarchical content structure arranges semantically and functionally similar portlets near by each other; and offering new Web pages for said Web Portal based on said new hierarchical content structure such that ones of said portlets within the same one of said plurality of resulting clusters are contained within the same one of said new Web pages.