Last modified: 2010-11-04 11:38:52 UTC
This was an artifact of a bad bit in the upgrade on en.wikipedia.org: message updates were done when we had an incomplete page table, then the page table was overwritten. The revision entries created thus have bogus rev_page pointers and are attached to seemingly random pages. They should be easy to identify and remove -- 'MediaWiki default' edits on non-MediaWiki: pages.
There were 622 such revisions, removed all of them.