Responsys (NASDAQ:MKTG) +10.5% and Marketo (NASDAQ:MKTO) +5.7% following news Salesforce (NYSE:CRM) is buying cloud marketing automation software rival ExactTarget for $2.5B (a 53% premium). Salesforce has long been expected to make a cloud marketing acquisition following Oracle's purchase of Eloqua, and the deal might pressure rivals (Microsoft? SAP?) to make a similar move. Salesforce promises to add ExactTarget's software to its Marketing Cloud platform, which includes social media marketing software from the Buddy Media and Radian6 acquisitions, as well as the Social.com app.