And if they don't?
Well, that's what serval will be for
The Wi-Fi Alliance has allied with the Wireless Broadband Alliance to sort out some standards for Wi-Fi roaming, taking its queue from the mobile industry, which does it so well. The details are still under development, but the idea is that a traveller will be able to just fire up their PC/tablet/smartphone and have it …
+1 for eduroam here - a worldwide roaming agreement for wifi hotspots already working and in place - and uses EAP as this article suggested would/should be the way for it to work.
This is only for academic participants - and the actual technology driving it is always being reviewed and updated - eduroam pushes some tech further than its been done before and the shortcomings have been noted.
Eduroam is great when it works, but over the last week I've had 50% luck with it. My 'home' university is in Australia, and I'm using Eduroam in Norway. When there are authentication problems you are all out of luck.
I much prefer the automatic logon using 802.1x rather than captive HTTP pages, especially for mobile phones.
The City of Trondheim has wireless network coverage in the commercial area of town that the public pay for, but they also bring the NTNU university network and Edurom into the area. Such foresight is appreciated and it is great to have my phone be able to check email with Wifi rather than roaming data.