Release notes:

I’ve written an ALSA driver for the DS sound hardware, with some help from Parrot. This driver has been enabled in the builds with CF support, along with userspace applications: vplay – plays WAVs. vrec – records from the mic. mp3play – plays MP3s. Only 8bit playback is working at the moment, and recording is not implemented yet. Stereo support is implemented, but has not been tested.

http://www.dslinux.org/blogs/pepsiman/