Description of problem:
ibus's engine API changed with ibus-1.1.0.
So the ibus-chewing needs to be updated for that.
The revised source code can be seen at http://github.com/definite/ibus-chewing/downloads.
The ibus-chewing rpm is in rawhide. Will also be in F-10 as soon as ibus-devel-1.1 is available in F-10.