Seems there is new version: Musepack SV8 libs & tools (r475) Stable release of Musepack SV8 libraries and tools License: BSD/GNU LGPL Release date: 2011.08.10 http://files.musepack.net/source/musepack_src_r475.tar.gz
Based on versions for the surrounding libraries, the newest available release is 477. At the moment I cannot get it to build successfully.
Are you planning a new bump for this package?