This only applies to x86 and amd64 profiles. Adobe Acrobat Reader 8.1.1, which was released about 10 days ago, needs libgtkembedmoz.so for a proper functionality of html content rendering. This library is provided by mozilla-firefox, but NOT mozilla-firefox-bin (at least for amd64). acroread needs a 32bit-ABI-version of libgtkembedmoz.so. Users with 64bit userland can't provide this library without much hazzle (32bit chroot and so on). Users with 32bit userland who use mozilla-firefox-bin instead of compiling this monster on their own, might have problems, too.
This bug blocks bug #192527, which is tracking the version bumb of acroread-8.1.1.
Coo, and how are we supposed to do that? There's no such thing bundled in the tarball. https://bugzilla.mozilla.org/
Bug filed upstream. Watch http://bugzilla.mozilla.org/show_bug.cgi?id=397613
Thanks. ;)