Here is a good article that explains the leglity of promoting gambling sites
http://www.ecommercetimes.com/rsstory/42696.html
Excerpt from the article:
"Even so, the DOJ has maintained that Internet gaming advertisements, like online gaming itself, are illegal and that "anyone carrying them could be charged with aiding and abetting." Specifically, the department states that such advertisements are in violation of the Interstate Telephone Act of 1964 and that online gambling operators are violating the federal Wire Wager Act of 1961.
The DOJ has made good on its claims of illegality by issuing subpoenas to many well-known media outlets to stop them from running ads for online gaming. The most recent group of subpoenas were handed out on April 12 to Esquire magazine in regards to an eight-page insert billed as the "Gentleman's Guide to Poker" and sponsored by BoDog Poker."