deepeshbanerji - 5:55 pm on Mar 21, 2010 (gmt 0) [edited by: Robert_Charlton at 6:16 pm (utc) on Mar 21, 2010]
Our tech team accidently added an inadvertant Canonical Tag onto 1000+ forums-type pages...
These pages were generating about 2000 long tail Google Visits a day and after we accidently introduced a canoncial tag in there we lost all the traffic. We realized the mistake 2 days after the change went live (the traffic started dropping almost immediately) and reverted the change.
The traffic has still not come back!
Be careful with the canonical tag.
[edited by: Robert_Charlton at 6:16 pm (utc) on Mar 21, 2010]