If you do searches on Bing, you'll see there is indeed PPC ads. Most search engines do, that's how they monetize the site. Bing used to be MSN and their PPC service is found at adcenter.microsoft.com. There are a lot of similarities with Google Adwords, if you've ever used it. So if you have, should be not much of a problem.
Yes Bing has started this service one year before. Bing PPC ads are cost lesser than google ads and their PPC advertising is limited to certain countries like US, UK, singapore.May be in future they will expand this PPC network.
yes Bing is former MSN and they have now joined yahoo to form one big PPC network. Lot's of potential right now to cash in on this traffic source.