Looking at the LibraryLink examples, there are several new functions and objects, as well as example programs, that appeared in version 9. Are these documented? If yes, where?

If would be nice to have a summary of the new features available, and a summary of how and when to use them, so people can more easily decide whether there is something that's useful for their project.

• MInputStream and MOutputStream types, WolframStreamLibrary.h header
• DataStore type
• WolframIOLibrary_Functions (comparable to WolframLibraryData, contains function pointers)
• all the async-*.c examples which use these features
@OleksandrR. I was thinking they might also be related to the AsynchronousTasks functionality of v9, and the DataStore might provide a way to temporarily store the results before they're ready to be returned. –  Szabolcs Sep 4 '13 at 14:41