[winduff]

you could add the following condition:

<if condition="$bbuserinfo[usergroupid] == x">

wich would mean, the twitter function would only be shown if the usergroup is x

for example:

<if condition="$profilefield[title]=='Twitter'">
<if condition="$bbuserinfo[usergroupid] == 1 OR $bbuserinfo[usergroupid] == 2">
<dt class="smallfont"><strong>$profilefield[title]</strong>:</dt>
<div id="twitter_div">
<ul id="twitter_update_list"></ul></div>
<script type="text/javascript" src="http://twitter.com/javascripts/blogger.js"></script>
<script text="text/javascript" src="http://twitter.com/statuses/user_timeline/$profilefield[value].json?callback=twitterCallback2&count=3"></script>
<br><dt class="smallfont">You can add me to your friendslist, my username is <strong>$profilefield[value]</strong></dt>
</if>
<else />
<dt class="smallfont"><strong>$profilefield[title]</strong>:</dt>
<dd class="smallfont">$profilefield[value]</dd>
</if>

you can add as many OR's as you like, wich would mean ( in this example) usergroups 1 and 2 can use this function. Any other usergroup who set a twitter account would just not show up