Yahoo!'s new online advertising system, Panama, scored a big win today with an exclusive, multi-year agreement to provide all the advertising for Viacom's Web sites, including sponsored search and contextual ads. The sites include MTV.com, comedycentral.com and Nickelodeon.com.

Viacom's sites saw about 90 million unique viewers in February. Not a bad haul for Yahoo!

This Marketwatch article mentions why Viacom wouldn't have given the deal to Google -- Viacom is suing Google-owned YouTube for copyright infringement -- but what about Microsoft? Is Yahoo!'s win a loss for Redmond?