[TundraSoul]

Here's my code, which works very well.

<vb:if condition="$post[postcount] == 1">
<vb:if condition="is_member_of($bbuserinfo, 1)">

<script type="text/javascript"><!--
google_ad_client = "your pub ID here";
/* 468x60, created 5/14/11 */
google_ad_slot = "my ad channel";
google_ad_width = 468;
google_ad_height = 60;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script><br />
<p><small>Register Now! Members do not see advertisements.</small></p></vb:if></vb:if>

I even added a little note at the bottom of the ad to encourage users to register. The code works perfectly on 4.13 and I use postbit_legacy.

Enjoy!