early in the F13 cycle, we enabled the bytecode interpreter in our
freetype package, since the patents on that have expired last fall.
Unfortunately, it turned out that many free fonts don't actually benefit
from this, and actually look worse with the bci. The reason for that is
that without the bci, freetype uses its autohinter on all fonts, but
with the bci turned on, it only applies hints to fonts which have them,
and leaves other fonts alone.
Behdad investigated the situation, and we have a plan to fix this, but
doing it properly requires enhancements in multiple places (freetype,
fontconfig, pango), and will not be ready in time for F13.
Therefore, we decided to turn the bci off again until the necessary
changes are in place to use it only on fonts which benefit from it. This
change went into freetype-2.3.11-3.fc13.
If your fonts look subtly different tomorrow, this is why...