Created attachment 5135 Fix typo to fix plugin build. I think there's a typo in panel-plugin/Makefile.am. It mentions libcpugraph_la_LDFLAGS instead of libcpufreq_la_LDFLAGS. I've created a simple patch to fix it.
Yes, a stupid typo that went unnoticed because it built fine here. I hope it was the only one. Fixed in http://git.xfce.org/panel-plugins/xfce4-cpufreq-plugin/commit/?id=76ffedc78bf2b4a38facb7c53eb2c2dd1d19c445, thanks for your report and the patch. I'll leave this open for a few days so that other people will find it easily.
Fixed a while ago, so closing now.