O Neal Gafter (Google) atualizou a sintaxe de closures.
Ele está estudando isso, juntamente com o Gilad Bracha e o Peter von der Ahé (Sun). O James Gosling aparece também na proposta, mas não sei se ele "apita muito" nessa questão.
http://gafter.blogspot.com/2006/09/debate-over-closures-for-java.html
Neal Gafter wrote:
This latest revision of the proposal drops local functions and the special nonlocal return syntax, adds support for generic type parameters that can be used to represent thrown exceptions, and has only one form of closure literal. It also adds an abbreviated invocation statement that supports very convenient control abstraction. Soon I'll present a parallel proposal based on interfaces (that is, without function types) and contrast the two proposals.
Postem no blog do Neal se tiverem alguma sugestão.