I found a threw about it but it was closed. I have been using Pubcenter in my Windows Phone and Windows Store apps for a few months and the payout is great as they pay per impression. It is better than any other ad service for apps that I have used.
I contacted one of my buddies at Microsoft but he was not sure if Pubcenter ads could be used on the web. I can't find anything in my Pubcenter account that suggests the ads can be utilized on a web page.