http://wikixmldb.dyndns.org/

We have parsed English Wikipedia into a well-structured XML
document (21 Gb in size) and loaded it into Sedna XML
database (http://modis.ispras.ru/sedna). With WikiXMLDB
demo you can run predefined or your own XQuery queries via
Web interface.

Querying Wikipedia in XQuery allows you to implement many
interesting applications. Read “Use case” section
(http://wikixmldb.dyndns.org/help/use-cases) for more
details.

Enjoy it!

Some refs you might wish to include (BibTeX format):

@INPROCEEDINGS{Minier2007,
author = {Minier, Zsolt and Bodo, Zalan and Csato, Lehel},
title = {Wikipedia-Based Kernels for Text Categorization},
booktitle = {International Symposium on Symbolic and Numeric Algorithms for Scientific
Computing},
year = {2007},
pages = {157–164},
address = {Timisoara, Romania},
url = {http://ieeexplore.ieee.org/iel5/4438060/4438061/04438094.pdf?tp=&isnumber=&arnumber=4438094}
}

@INPROCEEDINGS{Picca2007,
author = {Davide Picca and Adrian Popescu},
title = {Using Wikipedia and supersense tagging for semi-automatic complex
taxonomy construction},
booktitle = {RANLP 2007, CALP workshop},
year = {2007},
address = {Borovets, Bulgaria},
url = {http://moromete.net/articles/picca_et_al_calp07_cr.pdf}
}

@INCOLLECTION{Wang2007,
author = {Gang Wang and Huajie Zhang and Haofen Wang and Yong Yu},
title = {Enhancing Relation Extraction by Eliciting Selectional Constraint
Features from {Wikipedia}},
booktitle = {Natural Language Processing and Information Systems},
publisher = {Springer},
year = {2007},
volume = {4592},
series = {Lecture Notes in Computer Science},
pages = {329–340},
doi = {10.1007/978-3-540-73351-5\_29},
journal = {Natural Language Processing and Information Systems},
url = {http://dx.doi.org/10.1007/978-3-540-73351-5\_29}
}

@INPROCEEDINGS{Weaver2006,
author = {Gabriel Weaver and Barbara Strickland and Gregory Crane},
title = {Quantifying the accuracy of relational statements in {Wikipedia}:
a methodology},
booktitle = {JCDL ‘06: Proceedings of the 6th ACM/IEEE-CS joint conference on
Digital libraries},
year = {2006},
pages = {358–358},
address = {New York, NY, USA},
publisher = {ACM},
doi = {http://doi.acm.org/10.1145/1141753.1141853},
isbn = {1-59593-354-9},
location = {Chapel Hill, NC, USA},
}

@INPROCEEDINGS{Wu2008,
author = {Fei Wu and Daniel S. Weld},
title = {Automatically Refining the {Wikipedia} Infobox Ontology},
booktitle = {17th International World Wide Web Conference},
year = {2008},
address = {Beijing, China},
month = {April},
url = {http://www.cs.washington.edu/ai/iwp/publications/www08.pdf}
}

@INPROCEEDINGS{Zesch2007,
author = {Torsten Zesch and Iryna Gurevych and Max Mühlhäuser},
title = {Comparing {Wikipedia} and {German} {WordNet} by Evaluating Semantic
Relatedness on Multiple Datasets},
booktitle = {NAACL-HLT},
year = {2007},
owner = {Joel},
timestamp = {2008.03.26},
url = {http://elara.tk.informatik.tu-darmstadt.de/publications/2007/hlt-short.pdf}
}

Piotr