According to this recently posted paper, the order of your name in a co-authored article may have an effect on your career. Here is the abstract for Mirjam Van Praag & B.M.S. Van Praag, "The Benefits of Being Economics Professor A (and Not Z)":
Alphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced a faster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.
(Many thanks to Danny Sokol for the tip.) Perhaps Mirjam and B.M.S. are married; because of the ordering of the names, I would presume that Mirjam did more work on the article.