The new API level 9 of Android 2.3 brings with it a “Native access to Activity lifecycle” : it allows developers to write an Android Application with absolutely no Java coding, by the use of a provided Java Class “NativeActivity“. A “native-activity” sample gives you an example of making use of it through the “native_app_glue”, a C-only wrapper (see also my experiments on NativeActivity).
At the same time this revision r5 of the NDK is becoming interesting for me, with the first official support of C++ exception and RTTI. There is also a way to get a “standalone toolchain” with GCC 4.3, which give the ability to use only standard cross-compiler command (make) instead of the specific Android.mk files.
All this is not really well documented… You get plenty of example and sources, but there is not much in-code comments nor any “Native API Reference” available. In fact, even the documentation is not available directly on Internet: it is only provided on the NDK archive!
Edit: look at this Android Developer Blog post about Gingerbread NDK
Edit2: there is also a android-ndk Google group
Edit3: some other people share my enthusiasm about Gingerbread and the new NDK revision !