It's libvclplug_gtk680li.so.
During the installation of my 680_m30_ja build, OpenOffice.org 680 installation dialog said:
Error occured when copying the file libvclplug_gtk680li.so to /home/khirano/ooo/program
Retry, Ignore or Cancel?
I ignored, and then the installtion completed.
/home/khirano/ooo/program/soffice works fine.
I've filed an issue:
http://www.openoffice.org/issues/show_bug.cgi?id=26722