See Who's Editing Wikipedia: Diebold, the CIA, a Campaign
Inspired by news last year that Congress members' offices had been editing their own [Wikipedia] entries, Griffith says he got curious, and wanted to know whether big companies and other organizations were doing things in a similarly self-interested vein. ...
The result: ... a search tool that traces IP addresses of those who make Wikipedia changes ... [and] a database of 5.3 million edits, performed by 2.6 million organizations or individuals ranging from the CIA to Microsoft to Congressional offices, now linked to the edits they or someone at their organization's net address has made.
Some of this appears to be transparently self-interested, either adding positive, press release-like material to entries, or deleting whole swaths of critical material.