Just for the record, here's the comment I posted on java.net regarding the new closures proposal by Neal Gafter et al:
"Speaking of Closures, its hard not to agree with Josh Bloch on the new Closures proposal. He expressed serious concerns in his interview about further changing an already complex type system just to accommodate Closures. The current proposal seems more like engineering for the sake of it without thinking about the learning curve for a newbie. Open sourcing java will be mostly futile if we go the C++ way by introducing unnecessarily complex changes to the language based on the whims of theorists (even if they happen to be the pioneers in language theory). We need a more pragmatic solution that keeps in mind (the barriers to entry for) the average "Joe Java" as Josh says. The same way in which generics weren't over engineered to ape C++, we need a more practical approach to implementing Closures instead of merely looking to satiate the engineering appetite of a few individuals. "
The power of Java lies in its simplicity. We'd be killing the language by dragging it along the C++ path.