Here are my questions/concerns (and I know that no one is claiming this is universal solution to everything).
This type of thing is a [great but] local/temporary/band-aid to a systemic problem, and that mismatch, combined with the murky territory of gender, seems vulnerable to problems. How do transgender-ed people fit in this, they could certainly be/have been targeted by the same anti-math-stuff discrimination?
If you have a group/club for each under-represented demographic (female, black, trans, etc.), does that, in some way, promote some sort of isolationism?
What if this/a service/hacker-space is the only one in the area and/or the only one offering a specific thing (python vs ruby, or the only one with google glass or focused on UX)? Is it then still 'fair' to deny access to an individual based on something like their gender? Of course, females are systematically under-valued (if thats the right term) in this (and many other) fields, and so this is a drop in the ocean on the global gender/computer score board, and its not like it is their fault that no one else teaches UX or Lisp (having limited options at all to start with is sub-optimal), but it is not like said individual probably has anything to do with this type of repression. I guess this question regards how much the average 'male' (gender is vestigial and evil, see: post-genderism) human in computers has a leg up due to general repression.
This is not to dismiss the fact that having gender exclusive clubs might foster a more trusting or encouraging environment or something for some. Thank you for your time.