A young friend, recently engaged, passed on this story of the decline in married women keeping their maiden names.
The interesting statistics on American brides keeping their maiden names:
They also report a large, but probably not scientific, survey by TheKnot.com, which found that only 8% did in 2010.
The article suggests, by anecdote, that more women are using their maiden names as middle names for professional purposes, as Mrs. G. does.
I do remember noticing that among people we know, the trend seemed to peak with the late Baby Boomers of the college class of '77, but had was less common in our early Gen X cohort marrying in the early 1980s, even at a very politically correct college.