According to this story at PCMag, the updated MP3 format will become available later this year and will offer 5.1 output while still maintaining the compact file size. In case you didn't realize it, the current format is 2-channel stereo and although current soundcard drivers and software can usually mirror channels and play on rear speakers, it's still not 'true' surround.
The Fraunhofer Institute is also adding copyright protection to the format, coincidentally enough this week Microsoft has also unveiled their much awaited DRM (digital rights management) tools that are seen as a potential way to let subscription music services such as Napster and RealNetworks' Rhapsody move to portable MP3 players.
Will the new, not-so-flexible MP3 succeed? We will see.