Spotted this today — Bing is continuing to test more Google-like ad layouts. While Google has been serving their smaller “ad” labels for awhile now, Bing has stuck with their shaded layouts for the latter part of the last year. Now, it appears that’s changing with this new layout that’s showing much smaller “ad” labels with much less contrast with the rest of the page. Honestly, it’s very hard to tell that these are even ads if you aren’t carefully looking at the left hand side of this text boxes.
I’ll keep an eye on my Bing searches to see if I continue to get this newer style or if it’s a more limited testing ring.