I very seldom post on this board, but I felt that since my posting about names that have gone "the other way" is fact-based, I decided to repeat the post over here.
One time, someone was asking if there were any names that have gone from primarily female to primarily male. I did some looking, and I found no traditionally girl's names that were taken over by the boys, but I did find two boy-girl-boy names.
One of those was Elisha. It is a male biblical name (and so it has been recognized as a male name for thousands of years). It was in the U.S. top 1000 for males during the first three decades of the 20th century, and then fell out. It then appeared as a girl's name during the 1970s, peaking in the 1980s at #460, and fell out of the girl's category in the late 1990s. On the other hand, while Elisha declined on the girl's side, it started to reappear on the boy's side. As of 2003, the name is #612 in the boy's category and not at all on the girl's side.
Another boy-girl-boy name I found was Jan. It was first a male name in the 1900s, then fell out. The name reappeared on each side in the 1930s, but rose more quickly on the girl's side. The name peaked on the girl's side at #145 in the 1950s, and started to decline as a boy's name (as is typical). However, when the name fell out of the girl's equation in the 1980s, Jan began to pick up on the boy's side, and as of 2003 was #546 for boys, but not in the top 1000 for girls.