Honda #Pintermission (Pinterest)
The goals of campaign were to drive awareness to the newly created Honda Pinterest account, while encouraging followers to "get out and live life to the fullest." The brand also sought to deliver personalized messages in order to build relationships with followers. Here's how the campaign was implemented on Pinterest:

Honda offered $500 each to the most active pinners (as identified by Mashable) to take a 24-hour break from Pinterest (a "Pintermission," if you will) to go out and do what they've been pinning about doing. Each pinner also received a personalized invitation and, if they accepted, they had to set up a personal #Pintermission board where they shared photos of their 24-hour Pinterest break (not during the break, of course).

Why this is one of the best social media campaigns of 2012:
Honda's use of Pinterest was very creative and innovative. The message of the contest corresponded with Honda's messaging (particularly around its new CR-V) to get out and live life. It's also fascinating to build a campaign on a platform that encourages users to take a break from that platform. And then, of course, encourage those who took the break to share what they did on their day off.
Source: Simply Zesty