The JDK 7 development schedule is divided into a sequence of milestone cycles, most five to ten builds in length, with builds occuring roughly once each week. There will be no formal beta or early-access releases, as in the past. Major features and other potentially-destabilizing changes will targeted for integration early in a specific milestone.
Here is the current high-level milestone schedule, with the features targeted to each cycle:
One or more release-candidate builds will be declared after the last scheduled build, aiming for the General Availability release on 2011/7/28.