Three weeks back Google Rolled out an algorithm change that changed the way they evaluate link value.

Read here

Two weeks back they declare that over optimization will be punishable by death, or something similar to that. More here.

This week they rolled out a Panda 3.whatever update. And today when we search for "ajax based forums" we get this. To hell with your tall and fat and airy claims Matt Cutts. here is reality.