Nero has officially announced the release of their free Nero Digital Audio encoding software. This command line utility will take your .WAV files and encode them using the MP4 format.
Nero, the leaders in digital media technology, today announced that the Nero Digital Audio reference quality MPEG-4 audio encoding software is now available free of charge via download from the company's website (www.nero.com). Fully compatible with the latest MPEG-4 audio standard (LC-AAC, HE-AAC and HE-AAC v2), the 3GPP-compatible software enables users to store an entire audio album in a single .mp4 file with the best audio quality available.

A simple text-based command-line interface ensures that Nero Digital Audio is compatible with any existing audio software that consumers may already be using. Every file saved in the Nero Digital Audio codec will have advanced content management built into it, including support for CD-audio index maps, embedded album art and ReplayGain.
If you'd like to check it out, the Nero Digital Audio encoding software can be downloaded here. Otherwise more information is available on Nero's website.