I had set aside work on the closures prototype for a couple of months to write a JSR proposal that represents a consensus among the folks thinking about this area. You can find it at http://www.javac.info/consensus-closures-jsr.html. One of the things I learned is that unanimous agreement is rarely possible. There are those who feel that nothing should be done to the Java programming language, and such people will not be swayed by simple but powerful additions. Our latest JSR proposal comes as close to achieving consensus as I believe possible. All but one of the authors of the three widely-discussed closures proposals have agreed to support it.
The purpose of the JSR proposal is to define the problems to be solved and circumscribe the permitted solution space. It doesn't mandate a particular solution, though it does offer the Closures for Java specification as an example of a solution to many (but not all) of the problems. This should not be surprising, as that spec was written specifically in an attempt to satisfy the requirements. Still, the spec is a work in progress.
So what is next? I hope we'll have some active discussion at JavaOne about where to go from here.