According to Tom Warren at WinRumours.com this is part of a huge campaign that is about to kick off in earnest:
Cloud Power will appear in print, online, radio and TV commercials over the next several weeks. The adverts will roll out globally in magazines, newspapers, billboards and airport signs. The ads will feature three of Microsoft’s core cloud computing technologies: Office 365, Windows Azure and Windows Server Hyper-V. The first billboards have already begun hanging at Seattle’s Sea-Tac airport over the weekend. The campaign is expected to cost Microsoft several hundred million dollars. Microsoft’s consumer campaign “To the Cloud” is already running across the web and TV and focuses on the consumer offerings for cloud based computing.