On this score, Butler is on the stronger ground. For the benefit of those who don't know, there is an e-list called Marxism-Feminism (moderated by Martha Gimenez, Carrol Cox, and Malgosia Askanas), to which some of the lbo posters are also subscribed (e.g. Doug, Beth, Charles, Katha, Peter v H, Kelley, Michael H, yours truly, etc.). I dare say M-Fem must be one of the quietest left e-lists. It perhaps says something about the lack of interest in the practical synthesis of Marxism and feminism.
That said, Butler doesn't sound too interested in Marxism, practically or theoretically. Generally speaking, late modernists define their politics _against_ Marxism.