The adCenter Blog has an open invitation to register for U.S. Content Ads. So if you are an adCenter advertiser and you want your ads to be found on Microsoft's contextual network, you can apply for an invite here. Note, this is not for publishers to sign up with Content Ads, but for advertisers to sign up to place their existing ads on Content Ads. I have already begun testing Content Ads myself. More details on content ads here.
Save up to $400! Register now for SES New York 2012, the Leading Search & Social Marketing Event, taking place March 19-23. Google's Digital Marketing Evangelist Avinash Kaushik will keynote. Hurry, pre-agenda rate expires March 2!