Well, not user-correlated via traditional means. DDG is proxying user queries over to MS, but unless they're taking steps to actively fuzz the queries, there's all kinds of secondary signal MS could possibly be sampling out by correlating queries across time (especially since DDG also vends Microsoft-provided ads in the sidebar; it's unclear what signals MS is receiving about a user's session from DDG via server-to-server communication, or how MS might correlate that data. If MS vends an ad and the user clicks through, and MS gets signal that the user clicked on the ad from DDG, MS can correlate that the user who saw ad Y did search X).