MongoDB 2.5.0 is now available for testing.
As a reminder, 2.5.0 is a development release and is not intended for production use.
The 2.5 series will evolve into 2.6, which will be for production.
Notable features:
SERVER-8536: Background indexing on secondaries
SERVER-6157: New implementation of external sort
SERVER-6400: Matcher rewrite
SERVER-8464: Add support for building from source with particular C++11 compilers
If you have any questions, please let us know,
Dan