Well, I'm back in the USA, and at yet another Airport hotspot-- this time it's T-Mobile, and still I can't get on.
I did try pinging www.telltalegames.com
, and sure enough, I can't (though I can ping google.com and a bunch of other web sites, though not all).
From my limited sample, I would say that this is the rule for public WiFi areas, not the exception. I'm about to try to connect to the boingo hotspot and see if that works; I will also try tethering my mobile phone, but it's on t-mobile as well so I'm not hopeful.