Opus is a great new format with excellent audio quality even at extremely low bitrates (nice for music even at 48 kbps). This makes it a highly appealing codec for portables, especially for those with limited storage. Yeah, like all current WP7 handsets.

You can perform a quick test. Just download foobar2000 and opus-tools, convert some music at 48kbps, and hear the awesomeness.

If Opus support was added, we could carry much more music with the same storage. Skype will also be using this, so instead of supporting it just in Skype, they could add support for this in the underlying framework instead.

You can cast your votes for this feature at UserVoice.