[hakl]

It's compliant with FSF's definition of free software (http://www.gnu.org/philosophy/free-sw.html) and Debian's guidelines (http://www.debian.org/social_contract).

Stallman himself agreed that it was a good thing for Xiph to relicense their libraries from the LGPL to a permissive free software license (http://lists.xiph.org/pipermail/icecast-dev/2001-February/00...):

In response to the change of license, Richard Stallman of the Free Software Foundation says, "I agree. It is wise to make some of the Ogg Vorbis code available for use in proprietary software, so that commercial companies doing proprietary software will use it, and help Vorbis succeed in competition with other formats that would be restricted against our use."

[spiffworks]

Well, we're talking about two things, really- the webm reference implementation and the license under which the patents covering the spec are licensed. I guess the reference implementation is free as in freedom, and the spec is free as in beer to re-implement. This is why 'free standard' is such a pithy and accurate description.