There is some news about the STIX fonts. It looks like they will be releasing
a beta sometime in October (translation: November-December). At this time,
they have a draft copy of the license up on their website and are welcoming
comments.
http://www.stixfonts.org/user_license.html
What I saw was encouraging, but maybe somebody else might see something that
concerns bundling and distributing with MPL.
Darren