Today I released the first stable 1.0 version of the Teensy Audio Library.
http://www.pjrc.com/teensy/td_libs_Audio.html
It only works on Teensy 3.1 (hopefully "other" software development is ok). It brings pretty incredible audio processing capability to Arduino sketches. It can process many simultaneous 16 bit, 44.1 kHz audio streams, all automatically, while your Arduino sketch runs and calls its functions to changes settings, start/stop sound, get analysis results, etc.
If anyone's planning sound projects, I hope you'll take a look. More and 1 year of development has gone into this library, to bring high quality audio processing to sketches like never before.