How can a non-privileged user find the NIC speeds?

Does anyone know how to determine the NIC speed by non-privileged users?
I want to be able to do this from perl and can't find any data
structures in /proc and /sys, but then again there are an awful lot of
them and could be easy to miss in an obscure place. I usually use
ethtool for this but it requires privs.
-mark