Wilburforce - 5:01 pm on Dec 18, 2013 (gmt 0)
I'm not seeing anything different on my site - still in the doldrums - but a couple of Google searches I have tried in the last few days have yielded similar results to a few months ago. The synonym is back in evidence (I haven't noticed any improvement in accuracy).
Also there is the News phenomenon that Dymero reported a few days ago.
Possible they are re-testing whatever they were trying out (and by the look of it, abandoned in the meantime) in August.