From: kalinix calin.kalinix.cosma@gmail.com
Actually you have to have python-dateutil installed (probably a missing dependency) and the command should be ran as: yum changelog <date>|<number>|all [PACKAGE|all|installed|updates|extras|obsoletes|recent]
I saw this redhat bugfix: "If "yum changelog" or "yum update <package> --changelog" was run without the Python dateutils module available, yum-changelog would exit with a Python traceback. This package includes a patch which causes yum-changelog to fail gracefully." So I guess it is not mandatory... But, while the yum-changelog is from centos, the python-dateutil is from rpmforge...
Thx, JD