According to Tech crunch, Viacom has inked a $500 million ad deal with microsoft:

Here is the short version of todayís deal. (Bear with me). Microsoftís Atlas business (part of recently purchased aQuantive) will serve display ads across Viacomís U.S. sites, which include MTV.com and ComedyCentral.com, and get an exclusive right to sell remnant inventory as well. The value of the deal is $500 million to Microsoft, but it is hard to tell exactly where that comes from because there was a lot of bartering going on. For instance, as part of the deal, Microsoft agreed to purchase TV ads on Viacomís cable networks like MTV, Comedy Central, and BET, as well as some of those online ads that it will be serving. Microsoft will also license video from Viacom TV shows and movies on MSN. (Round and round is the name of the game . . . ). So the $500 million is most likely the net amount after the value of all of these sub-deals were calculated