After re-reading the statute, I'm realizing that the provision relating to blocking access to the sites is very odd, and possibly altogether impotent.
Nothing in the main operative provision -- s. 5363 -- imposes any obligations on anyone other than parties accepting financial transactions in connection with unlawful internet gambling. Neither that section nor any other contains any affirmative obligation for ISPs (other than not knowingly allowing illegal transactions).
Blocking access to the sites comes in only in the Civil remedies section, s. 5364(c). Even there, though, no affirmative obligation is placed on the ISPs. All it says is that any civil relief against "interactive service providers" "SHALL BE LIMITED" to "the removal of or disabling of access to, an online site violating s. 5363, or a hypertext link to an online site violating such section, that resides on a computer server that such service controls or operates . . . ."
Two important things occur to me:
1. Neither the Attorney General nor anyone else has actually been directed to stop ISPs from allowing access to sites; all the statute does is state that in crafting a civil remedy, at most (when it comes to ISPs) a district court may direct the ISP to block access. What that means is that a federal prosecutor would probably have to name the ISP in any suit against a site violating 5363 (which is probably not something they'd really want to do in most cases) and then argue that in order to stop the violation of S.5363 (illegal financial transacations), access to an internet site should be stopped entirely. Many judges would be very predisposed not to block access to internet sites if less restrictive remedies could be crafted, and in most circumstances one would think they could be. So here we have pretty significant substantive and procedural hurdles to actually getting sites blocked.
2. The "that resides on a computer server that such service controls or operates" is really weird. It's not clear what that phrase modifies exactly -- the "hyperlink" or the "on-line site violationg s. 5363". If it's interpreted to modify the latter -- and given the punctuation, specifically the placement of the commas, it sure seems like it's the latter that it's intended to modify -- then I assume none of the sites reside on or are controlled by the ISP, and so the subsection would never apply. Maybe the word "resides" means something else in this context?
Perhaps not quite on point but an interesting factoid:
As of about 2 months ago when I was in India both PartyPoker and PokerStars themselves block access to Indian IP's. THis is because gambling is illegal in India. I emailed Party and they confirmed that the actually do block access to any indian IP address.