[Lynne]

Well, in the postbit (or postbit_legacy), you could do something like this in the message area. This makes the text green for all admin posts (they are in usergroup 6):

         <!-- message -->
<if condition="is_member_of($post,6)">
        <div id="post_message_$post[postid]" style="color:green;">$post[message]</div>
<else />
        <div id="post_message_$post[postid]">$post[message]</div>
</if>
        <!-- / message -->