One of the big successes of the last 18 months has been Google image ads (launched as PLAs, now transitioning to Shopping campaigns). With Bing playing catch up on the success of these campaigns, it finally launched Bing Product Ads in the USA earlier this year.
As yet, these campaigns are only available to US based advertisers, but expect to see them in the UK soon. Once launched, this will be a compelling reason for e-commerce AdWords clients to begin advertising on the Bing network.