Google quietly announced in May that any AdWords Remarketing activity would automatically be eligible to show on cross exchange inventory. I am not sure how much additional inventory that ads to the already huge pool of inventory that was available through the DoubleClick ad exchange, but it is another step in the right direction for Adwords Remarketing.

The next big question is when will it become user based instead of cookie based? When or if that happens, Adwords Remarketing will have a significant edge on most of its’ direct competitors.

Here is the official Adwords blog post.