The hive vagina was a joke term used by some members of the geekfeminism.org community to indicate a mock group-mind. It's similar to the geek concept of the cabal in the phrase there is no cabal, a (usually non-existent) group of powerful insiders secretly controlling a community.
Not all feminists, nor all women, have vaginas. The term is therefore exclusionary. It seems to have fallen out of popular use in the community ca. 2014.