Recent reports from Wired and Daily Kos discussed attempts by certain organizations (Fox News, Diebold, Wal-Mart, ExxonMobil, the CIA, and the U.S. House of Representatives) to redefine reality by editing Wikipedia articles in their favor.
While it's interesting we all know this now, the problem is that we all know this now, and the even the stupid evil-doers will learn about IP addresses. For more see:
Lost Remote's WikiScanner reveals anonymous Wikipedia editors
Crooks & Liars' An embarrassed Fox News hits Wikipedia