an eggdrop can perform a whois on the user to check whether it s identified, or even easier, use /ns status <nick>...
but besides that, imo it s definately not part of the core business of services, but sounds an interesting concent and on smaller nets, why not ?
jfyi: this doesn't mean i m volunteering to write it
[Edited on 12-1-2007 by Viper]