AlyssaS - 11:50 pm on Nov 29, 2011 (gmt 0)
To be fair to Marissa Mayer - when she was in charge of the Google interface, the ads were clearly delineated. I think she was moved to look after maps in late 2010. And that's the point when G's interface started changing - all those tests at the start of this year, then the black bar at the top, and the yellow of the ad box fading to almost white, and the "sponsored links" changing to "ads".
Prior to that G's interface remained pretty constant for a decade, with only miniscule changes - maybe in her mind, because the old rules applied for so long, she felt they still had force.
No idea who is in charge of the interface at the moment (can't remember seeing an annoucement about it), but they definitely have a different view of how things should be done - and top management appears to support them.