Restrict Access to Public IM networks

I was wondering if there is a way to restrict access to the Public IM networks (IM, GTALK, YAHOO, MSN, etc) either on the client or server?

I don’t want the icons to show up on the Spark client of specific users or groups of users. We are using the LDAP integration.

Absolutely. If you go to the gateway tab you can set the permissions for each protocol: