They have
developed a method for disabling sperm in mice and are now seeing if it will work in humans. If the sperm can't swim, they will die before they even have a shot at attempting to fertilize an egg.
With regard to how this shapes power dynamics, I must first whip out the always-relevant (and eternally infamous) SMV graph:
The male pill erases the ability of women to baby-trap men of prime earning age. It also completely removes the need of any men to discriminate on the basis of trust in the sexual market. In today's environment, banging the wrong girl can end your financial life. I personally know of a guy who was baby trapped by a girl just six months ago (they're now "married.") That wouldn't have happened with male contraception and the girl would have likely been dumped.
Women's bargaining power is obliterated because the need for trust is greatly diminished. If a girl doesn't put out, she can be more easily replaced or substituted because there's no risk of knocking another girl up. This has significant implications for extramarital affairs. For example, none of us would remember John Edwards if male contraception had existed in 2008.
It also expands the market. I, personally, cannot be persuaded to bang a dumb chick. I wouldn't risk my child inheriting a low IQ, should contraception fail. Many others share this view (save for people who consider abortion a viable option). With the male pill, this concern is irrelevant since conception is rendered physically impossible. Any consenting and sufficiently attractive woman is acceptable.
This means responsible women and smart women lose bargaining power because those attributes are less valuable (in the short-run).
Now, if we add believable sexbots to the mix and men checking out, women lose out in the short-term market (players and other high-SMV men can pump & dump with even less risk) and the more narcissistic women lose their power over "thirsty" men because that thirst is satisfied by a surrogate that doesn't age, doesn't nag, and doesn't present any health or financial risk.
Moreover, a sexbot will not exploit the legal system to get revenge or reconcile regret.
Real, attractive, feminine women will still be at the top of the totem poll, but the development of the 'male pill' will effectively throw all other women straight to the wolves (and/or dregs).
I will also note that, because more and more people are both delaying marriage or foregoing it all together, the short-term implications cited above are the only things that matter insofar as women are converned. Sexual liberation, female "empowerment," and the advances in contraception are rapidly reducing women from highly valued members of society (mothers who raise children) to literal worker drones (see: women married to their career) who double as sex objects. Sexbots, being the ultimate progressive technology, will axe the latter and transform all but the most desirable women into mere labor pool participants.
As an aside: I am very bullish pharmaceuticals. Particularly companies that sell anti-depressants.