Have you seen the Keyword Forecast Tools from Microsoft adCenter Labs? “Learn about the impression count forecast and demographic predictions of your search terms.” I don’t know where or how Microsoft got this kind of data and how accurate it is, but it looks interesting nevertheless.
I typed in “yahoo store;yahoo merchant solutions” and the graph does seem to confirm that “Yahoo! Store” as a name/brand/product has stuck, despite the renaming effort to “Yahoo! Merchant Solutions”. The demographic data seems to show that interest in “Yahoo! Store” is spread equally between women and men, across all age groups.
P.S. Happy new year, by the way!