supply issue
If you had 50 software engineer positions to fill and auto-hired every woman who applied, you would still not come close to 50-50. There is still fundamentally a supply side issue. Look in any college tech class. Not many females in there.
I had a couple of entry level SE positions open back in the spring and got 600 applicants, mostly recent MS-CS grads. The women applicants were in the single digits. We did mange to hire one.
At JavaOne a couple of weeks ago I don't think you could fill a small room with the few women who were there.