From ABC News:

Women are a big step closer to serving on U.S. Navy submarines. ABC News has learned that the Navy has decided to lift the ban on female submarine crew members. Subs are one of the last places in the military from which women are excluded.
The only potential roadblock remaining is Congress. A 30-day window for congressional comment began Monday.
A Defense Department official tells ABC News that the civilian Secretary of the Navy, Ray Mabus, and the Chief of Naval Operations, Adm. Gary Roughead, support lifting the ban. Defense Secretary Robert Gates signed a letter last Friday notifying Congress of the Navy’s policy change. The 30-day window for congressional comment began when Gates’ letter was delivered to Capitol Hill.

Echoing what Kathryn says above, a former officer in the Silent Service e-mails with this:

If it helps, as a former submarine officer and acquisition guy, they are seemingly doing this smartly. They plan on putting the women on the Trident Submarines–much much bigger than fast attack submarines and better to handle special arrangements for berthing and use of showers/heads. Around the submarine community, it has been well known that about 8 females from the Naval Academy had been selected to begin the training (not much different than that given to female nuclear Surface Warriors).
FWIW. I think it could be sufficient if they kept them on Tridents, but “progress” always means pushing beyond sanity so it should be about 10 years before they are on fast attack boats too. I served on Fast attacks and think women on board would create a sexual harassment attorney’s career. The passageways are too thin for two male members to keep from brushing each other’s body, the berthing space is insufficient for the men on board and can not handle special dispensations that would be required for female sailors (Three sailors share two beds on a rotating basis & there is no place for segregated berthing or bathrooms.
Not sure if you were posting to get Elaine Donnelly’s blood pressure up, but the writing has been on the wall for quite some time.