Hi nice hack! it's got some potention in my opinion.
I have for example some plain text I only want to show at some places of my vbsite. so I place the $advert outthere and I copy the code within the plugin from "global_start" and than add the idusergroup numbers exept for id1 (guests). This way you probably tell that every idgroup does not see it.
Is there a way to invert that? so you just place the useridgroup-numbers who WILL see it? (it's just that it tires my mind to think the other way around i guess

)
further more...nice plugin