Microsoft, in their infinite wisdom, is now using MSN.com to do something that made Yahoo.com so successful in the first place. Since they've rebranded their search engine and donned it Bing, they've decided to take advantage of the MSN.com domain in another way. And they've unleashed an advertising campaign to bring you there.
MSN.com is now a portal, attached to the Bing search engine. I assume that it's meant to drive traffic to more Microsoft owned sites, where they can serve more ads, and create a content network which is larger, and attracts more people than before.
Yahoo used this same strategy to run themselves out of the fight for leading search engine. And with the most recent advertising stats released for the first quarter of 2011, Yahoo is now second to Google and Facebook is climbing fast and is right behind them for number 3 in display advertising dollars.
Good luck Microsoft. One of these days you'll figure out how to make money in the new economy!