Like me, you are probably an emerald user who upgraded to Ubuntu/Xubuntu/Kubuntu 11.04 (Natty Narwhal) only to find out that emerald crashes (segfaults) every time you try to start it.
The solution to resolve the issue is as follows:
apt-get -y install libtool
apt-get -y install build-essential
apt-get -y install intltool
apt-get -y install libdecoration0-dev
git clone git://anongit.compiz.org/fusion/decorators/emerald
git checkout -b compiz++ origin/compiz++
rm -rf emerald
There is another guide on the Ubuntu forums that tells you to apply a patch. I attempted to apply the patch but all 5 hunks failed. I went ahead with the compile anyways and it resolved the issue. It looks like the fix made it’s way in to the latest version in the git repository.
Good luck and enjoy.