Yes. It's called Microsoft PubCenter. On HubPages, it's part of the HP Ads program. Unlike AdSense that combines display ads from the doubleclick exchange, PubCenter is almost exclusively text ads. Microsoft has an exchange like product from the Aquantive acquisition and also has the DrivePM network, although it may be called something different.
Yahoo shut down it's contextual nextwork, and Blue Lithium that they acquired doesn't seem to be taking new publishers. For publishers to work with Yahoo, the best way is through Right Media (Yahoo owns it). Right Media is an ad exchange of sorts, but it requires publishers to signup under a buyer that has a seat on the exchange. In the HP Ads program, many Right Media exchange partners have access to the inventory and we even have a deal with Yahoo directly.