Paradox the issue is not cut and dry and open to legal interpertation. The discussion came to a fore front recently when a Portal owner was subpeoneaed by the Department of Justice to turn over financial and business records. It’s widely believed that the portal in question was targeting Online Sports betting and not casinos. You can read about the subpeona here:
http://www.igamingnews.com/index.cfm?page=artlisting&tid=4553
To read one law firms view point about the legality of Online Gambling Portals in the US go here:
http://www.lawrencewalters.com/advertising_casinos.php3
and here
http://www.lawrencewalters.com/gambling_ads.php3
It’s important to note that these papers are an interpertation and subject to error or legal challenge.