The deal has been completed. The last hurdle is now out of the way in Google's 11 month wait to purchase DoubleClick. The European Union has approved it.
Google has said it will be adding the DoubleClick technology and services as quickly as possible.
Google has indicated this will cause the loss of some DoubleClicks as it becomes part of Google. That reduction should start next month.
It is going to be interesting to see if this will be something that will help Google to start dominating display advertising the way it dominates search advertising.
There are lots of details and these articles have them:
Google closes deal of display-ad software - Salt Lake Tribune
InternetNews Realtime IT News – EU Approval Paves Way For Google-DoubleClick Ad Blitz
Google closes $3.1 billion DoubleClick deal