Amanda Marcotte debunks it:
For every study showing women talk more, there’s another showing men talk more. After a while, it becomes difficult to deny that individual preference and environmental pressures have more influence than gender on how much talking people do. (For instance, I work at home and my partner works in an office. Odds are really high that he speaks many times more words than I do on a regular basis, because he has to.)
So why do people so readily believe women talk more? Part of the problem is that our prejudices distort our observations about reality. Consider that most Americans overestimate how much of the population is gay by a factor of 5 and overestimate how much of the population has illegally immigrated here by a factor of 6 or 7. They also overestimate what percentage of the population is on welfare.