b) Also Jython is virtually dormant, at some older version of Python, while both JRuby and IronRuby are actively worked on.
c) Groovy hasn't added any support for invokedynamic or even started on it. A month ago they announced they're removing their meta-object protocol rework from the upcoming version 2.0.
SpringSource seem to be repositioning Groovy as a staticly-typed language, this year adding primitive types like in Java. Before everything was an object, and primitives were regarded as leaky abstractions. 2 months ago they employed someone to write a static type checker called "Grumpy" for Groovy, and eventually type inference and optimization, but the work's just started so it might take quite some time depending on how good their new hire is. This year they also tried to rewrite the Antlr 2.7 based parser in Antlr 3.2, using a Google Summer of Code worker, but they didn't get very far. Perhaps the static type checking for Groovy will be more successful, perhaps not.
I imagine this repositioning was instigated by the Grails team wanting a faster language, with dynamicity an optional extra to be used only when required.
I find it a bit of a dodge when a dynamic language has to go to static types for performance. That's not to say I haven't wanted to have that dodge available to JRuby users, but being unable (or unwilling) to unilaterally add optional static types to Ruby, we've been forced to find more creative options. We'll probably never approach Java's raw primitive math performance, but I think we can easily match Java's speed (and in some cases, already do) at manipulating objects.
It also appears that the push toward more static typing in Groovy may come at the cost of dynamicity...or at least incompatible changes in Groovy's dynamic features. Perhaps it's the best move for them, though; they've always pushed Groovy's ability to run (and enhance) plain old Java code, but performance was considerably worse than Java.
It's unfortunate that other JVM dynamic languages did not start exploring invokedynamic sooner. It has been a complete game-changer for JRuby.
c) Groovy hasn't added any support for invokedynamic or even started on it. A month ago they announced they're removing their meta-object protocol rework from the upcoming version 2.0.
SpringSource seem to be repositioning Groovy as a staticly-typed language, this year adding primitive types like in Java. Before everything was an object, and primitives were regarded as leaky abstractions. 2 months ago they employed someone to write a static type checker called "Grumpy" for Groovy, and eventually type inference and optimization, but the work's just started so it might take quite some time depending on how good their new hire is. This year they also tried to rewrite the Antlr 2.7 based parser in Antlr 3.2, using a Google Summer of Code worker, but they didn't get very far. Perhaps the static type checking for Groovy will be more successful, perhaps not.
I imagine this repositioning was instigated by the Grails team wanting a faster language, with dynamicity an optional extra to be used only when required.