The Matroska team has released libebml v0.8.0 and libmatroska v0.9.0. These releases mostly add new macros and API entries to make a smooth transition to libebml2 & libmatroska2 that are coded in C (with a C++ legacy layer). It also fixes a memory freeing bug that was triggered in VLC. The next MKVToolNix release will require the new versions of both libraries.
Nothing should have changed from a package maintainer’s point of view.
Binary packages for Debian, Ubuntu, Fedora Core and OpenSuSE are available at the MKVToolNix downloads page.