What? Grand Central Dispatch is a lot easier to work with than most explicit threading mechanisms and with the new block support is a lot less verbose than the typical Java thread-based approach.
Java/C# don't need a language extension - the functionality exists outside the semantic boundary of the language. Another cludge in Objective-C.
C# (ThreadPool/async framework/Windows workflow) and Java (ExecutorService/lots of 3rd party frameworks) have had them for years with well-known communication, thread safe data structures, concurrency and locking semantics.
Most of the verbose mess you see in Java threads is because the person writing it doesn't know much.