If I enter the following:

 

<script type="text/javascript"><!--
google_ad_client = "pub-8037121247057075";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_ad_type = "text_image";
google_ad_channel ="";
google_color_border = "F7E2C7";
google_color_bg = "F7E2C7";
google_color_link = "663300";
google_color_url = "CC9900";
google_color_text = "000000";
//--></script>
  <script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
  
</script>

 

I get this as the result when I check HTML:

 

<iframe name=google_ads_frame marginWidth=0 marginHeight=0 src="http://pagead2.googlesyndication.com/pagead/ads?client=ca-pub-8037121247057075&amp;dt=1130494979288&amp;lmt=1130494979&amp;format=468x60_as&amp;output=html&amp;url=http%3A%2F%2Fdevelopment.smallbizserver.net%2FDefault.aspx%3Ftabid%3D53%26forumid%3D1%26view%3Dpost&amp;color_bg=F7E2C7&amp;color_text=000000&amp;color_link=663300&amp;color_url=CC9900&amp;color_border=F7E2C7&amp;ad_type=text_image&amp;u_h=1050&amp;u_w=1400&amp;u_ah=1022&amp;u_aw=1400&amp;u_cd=32&amp;u_tz=120&amp;u_his=4&amp;u_java=true" frameBorder=0 width=468 scrolling=no height=60 allowTransparency></iframe>

 

Why is that?