An Australian couple was, indeed, notified via Facebook that they were going to lose their home, Rod Mcguirk of the Associated Press reported in December.
Also, many have lost their jobs thanks to posts on the site:
Exhibit A: Dan Leone lost his job with the Philadelphia Eagles for a status update.
Exhibit B: Virgin fired 13 flight attendants last year for "criticising the airline's flight safety standards and describing its passengers as 'chavs'" on Facebook.
You get the point, chav.