The answer to that question was signed into law today.
President Obama signed HR 2765, the "SPEECH Act," into law, codified at 28 USC Secs. 4101-4105.
The act prohibits US courts from enforcing foreign defamation judgments unless (1) the judgment would satisfy First Amendment or similar state constitutional protections, and (2) the foreign court making the ruling had jurisdiction that comports with our due process requirements. To get a US court to enforce the foreign judgment, the plaintiff bears the burden of proof that the judgment meets these standards. Effectively, these requirements will prevent a defamation plaintiff from forum-shopping globally; even if the plaintiff finds a more friendly jurisdiction, it will still have to satisfy US legal requirements for defamation before enforcing the US judgment here.
The act also applies 47 USC 230 to foreign judgments; if the subject information would have been protected by 47 USC 230 in the US, the plaintiff has the burden to show that the foreign judgment comports with 230. Very late in the drafting process, I raised a minor concern that the shield only applies to "providers of interactive computer services" and not ICS "users," even though 230 protects both providers and users. This is a minor drafting error, but I hope it will not result in any judgments that slip through the cracks. Also, the statute expressly pertains only to defamation claims; other causes of action do not get the shield, and usually multiple causes of action are asserted alongside a defamation claim.