Acknowledgement
We would like to thank our project partners for helpful comments and stimulating discussions. This work is done within the Webocracy project, which is supported by European Commission DG INFSO under the IST program, contract No. IST-1999-20364 and within the VEGA project 1/8131/01 Knowledge Technologies for Information Acquisition and Retrieval of Scientific Grant Agency of Ministry of Educationof the Slovak Republic. The content of this publication is the sole responsibility of the authors, and in no way represents the view of the European Commission or its services.