[nerbert]

Here's a crude way of doing it with template edits.

In postbit.css add this to the bottom:

/* markup for administrators  */

.postbit .group-6, postbitlegacy .group-6{
	color:red;
}

in the postbit template find line 42 and modify as follows:

                                <div class="username_container">
                                        <vb:if condition="$post['userid']">
                                                {vb:raw memberaction_dropdown}
                                                {vb:raw post.onlinestatus}
                                        <vb:else />
                                                <span class="username guest">{vb:raw post.username}</span>
                                        </vb:if>
                                        <span class="usertitle group-{vb:raw post.usergroupid}">
                                                {vb:raw post.usertitle}
                                        </span>
                                        <vb:if condition="$post['rank']">
                                                <span class="rank">{vb:raw post.rank}</span>
                                        </vb:if>

                                        {vb:raw template_hook.postbit_userinfo_left}
                                        <vb:if condition="$show['reputation']">
                                                <span class="postbit_reputation" id="repdisplay_{vb:raw post.postid}_{vb:raw post.userid}">{vb:raw post.reputationdisplay}</span>
                                        </vb:if>
                                        <vb:if condition="$post['userid']">
                                                <div class="imlinks">
                                                        {vb:raw post.icqicon} {vb:raw post.aimicon} {vb:raw post.msnicon} {vb:raw post.yahooicon} {vb:raw post.skypeicon}
                                                </div>
                                        </vb:if>
                                </div>

for postbit_legacy do similarly for line 33

		<div class="userinfo">
			<div class="username_container">
			<vb:if condition="$post['userid']">
				{vb:raw memberaction_dropdown}
				{vb:raw post.onlinestatus}
			<vb:else />
				<span class="username guest">{vb:raw post.musername}</span>
			</vb:if>
			</div>
			<span class="usertitle group-{vb:raw post.usergroupid}">
				{vb:raw post.usertitle}
			</span>
			<vb:if condition="$post['rank']">
				<span class="rank">{vb:raw post.rank}</span>
			</vb:if>
			{vb:raw template_hook.postbit_userinfo_left}
			<vb:if condition="$show['reputation']">
				<span class="postbit_reputation" id="repdisplay_{vb:raw post.postid}_{vb:raw post.userid}" title="{vb:raw post.username} {vb:raw post.level}">
					<vb:each from="reputationdisplay" value="row">
						<img class="{vb:raw row.class}" src="{vb:stylevar imgdir_reputation}/reputation_{vb:raw row.posneg}{vb:raw row.imgext}" alt="" />{vb:raw row.rowend}
					</vb:each>
				</span>
			</vb:if>
			<vb:if condition="$show['avatar']">
			<a class="postuseravatar" href="{vb:link member, {vb:raw post}}" title="{vb:rawphrase {vb:raw post['onlinestatusphrase']}, {vb:raw post.username}}">
				<img src="{vb:raw post.avatarurl}" alt="{vb:rawphrase xs_avatar, {vb:raw post.username}}" title="{vb:rawphrase xs_avatar, {vb:raw post.username}}" />
			</a>
			</vb:if>

I think I have the CSS right so it works in postbit legacy (I don't use it). By the same method you can write CSS for any group you want.