Hi,
this is a good question and could good be used if the event creator is not the contact person. But since the contact system is not very good linked with joomla (there are even plans and possibilities to uninstall it (like earlier the weblinks system), there will be a lot of work to add this with enabling and disabling, I fear.
I agree Jojo, sending emails to a Contact item is very complicated. This component maybe installed or not, the event may have a contact or not, with current Joomla the contact may relate to a user or not (if I remember right in J! 2.5 it was a must to specify a user), there maybe an email address or not, ... too many pitfalls and reasons for a lot of new posts here.
If you take a look on JEM's mailer plugin you'll see many alternatives: emails can be sent to administrators, to email addresses you typed in on one of event's categories, to members of a JEM group connected to one of event's categories, or simply to the creator/owner of the event. Depending on the amount of different contacts you need you may use JEM groups or make the corresponding user to event's creator. (because creators normally are permitted to edit their own stuff you should check and adapt the permissions to your needs, of course).
