The case can be made that slash is feminist because so much of it is, basically, porn written for women by other women, where historically women have been expected to either be pristinely lacking in sexual desire or only sexual for the express benefit of men rather than for themselves. At least, I would make that case. That, of course, is looking at slash fiction as a concept rather than the content of the fics, which is sadly often pretty sexist. Nobody internalizes sexism like a 15 year old girl on the internet, it seems.

If anything, slash teaches us that women's porn can be just as retarded as the guys' porn. That's equality, right?