Technically, the Pentagon has a lot of room to maneuver. They could simply revert back to standard practice and enforce the ban, continuing ongoing investigations, initiating new ones, refusing to accept gay applicants, and throwing away the applications of those who applied yesterday.
Or, they could take a softer approach. The Grand Bargain between the Pentagon and the White House has always been predicated on the Pentagon review process. The White House promised not to interfere, and the Pentagon, essentially, has promised to "process out" the gay ban. Where there have been bumps in the road, the Pentagon has expected the administration to stick to the agreed-upon process. So far, to the horror of gay rights activists, the White House has done precisely this. So now, some White House officials believe it's time for the Pentagon to show good will of its own.
This article available online at:
http://www.theatlantic.com/politics/archive/2010/10/dont-ask-dont-tell-guidance-expected/64935/