Can you clarify what you mean by this? Chat can only be used among members of your domain, which is why the users list displays ALL user accounts on the domain, as well as any aliases that have been enabled as a chat room. It may be tough to show regular Contacts here as well or instead, since Contacts can be created for external email addresses as well. When you say you want to "be able to see users once added to contact list," are you looking for a way to show only the specific GAL entries who are in your contacts list as well? Or are you essentially just looking for a way to add favorites to the user list so that only specific users show in the list at a time?
Personally, I prefer the navigation pane to display only the conversations that I'm actively participating in, not the entire list of users of the domain. But to accommodate that, we'd need to store a separate list of domain members and allow users to open and close conversations as they wish. It's possible that something like that may be considered in the future, though it's not available at the moment.
Can you clarify your thoughts please?