Actually, the chart was from Piketty – Not Even His Data Are Worth Anything (the whole article is well worth the read). Some other useful articles on this subject:

Inequality Used to Promote Wealth Grab by the State
A Monstrous Aberration
Is Capitalism Doomed?
What You Need to Know about the Wealth Inequality Debate

Also, I generally dislike Martin Armstrong's writings, but on this particular subject he is spot-on:

The Two Most Dangerous Ideas
Thomas Piketty – Another Economist on the loose out to DESTROY the World as We Know it.
Rock-Star Economist Piketty & His Bogus Data
Piketty – The Greatest Justification to Just Rob Anyone Who Has more Than You