I feel destined to have to go through the faults of this argument about the pay gap for many years to come. To keep it as short as I can, there are three problems with using a pay gap to justify further feminist struggle.
First, there is no pay gap in the sense of women being paid less for equivalent work. Men earn slightly more on average than women because they work longer full-time hours than women working full-time; because they are more likely to accept dangerous work or work in remote locations; and because they are more likely to choose better paying occupations.
There are two good brief articles I can recommend for those wanting more information on these matters: one by John Leo and another by Bettina Arndt.
John Leo points out that women are 15 times more likely than men to become executives at top corporations before the age of 40. In other words, those women available for these jobs are fast-tracked into them at a much younger age than their male counterparts. Leo, summarising some of the findings of a book on the subject by Warren Farrell, notes that:
Never-married, college-educated males who work full time make only 85 percent of what comparable women earn. Female pay exceeds male pay in more than 80 different fields, 39 of them large fields that offer good jobs, like financial analyst, engineering manager, sales engineer, statistician, surveying and mapping technicians, agricultural and food scientists, and aerospace engineers. A female investment banker's starting salary is 116 percent of a male's. Part-time female workers make $1.10 for every $1 earned by part-time males.
There is a worse problem with Gillard's argument about the pay gap. It is senseless to talk about a "male wage". The large majority of men work to provide for their families. The money they earn is effectively a family wage. Gillard falsely imposes a modernist assumption on men: that men are making money in competition with women for the autonomy and power that money brings. It is a vision of society in which men and women are naturally set apart in a hostile, competitive relationship, rather than working to raise a family together.
Finally, it may not be wise for women to wish for the abolition of the pay gap. Women are inclined to feel romantically attracted to men who earn more than they do. The less the pay gap, the less likely it is that a woman will find a husband. Also, for the pay gap to disappear, men will have to be less oriented to earning a good income to support their families (in terms of accepting longer full-time hours, or selecting well paid, rather than glamorous and rewarding occupations). Is this really in the interests of the average wife?