Heya,
Last week I resurrected Wikihadoop from the Summer of Research 2011 when we wrote a Hadoop-based input parser for bzipped XML dumps of Wikipedia and the ability to create diffs between revisions. This work was mainly done by Yusuke Matsubara, Aaron Halfaker and Fabian Kaelin.
This is working again and if you have input / suggestions on how to expose this data, then please let me know!
Best, Diederik