Latest versions lacks xfce4-power-information, typing "locate xfce4-power-information" outputs only "/usr/share/man/man1/xfce4-power-information.1.gz". My version is 1.4.4. In 1.2 this feature existed.
Something similar exists in settings, but there is no processor tab, where are displayed processes which consume power. http://forum.xfce.org/viewtopic.php?pid=40076#p40076