(http://i53.tinypic.com/2eol3s8.jpg)
To prevent ridiculous online bills while "on the road," Windows 8 hints at a cost limiter feature that allows admins (and end users, hopefully) to cap data transfers on 3G, 4G, WiFi and even WWAN connections. In -- still pretty early -- group policies I noticed that admins could choose between "Unrestricted", "Fixed" (the use of connection is unrestricted up to a certain cap) and "Variable" (connection is costed on a per byte basis) settings in order to keep mobile costs down.
Digging a bit further, I found that admins also have the choice to disable mobile roaming connections for their clients altogether. It's quite obvious that Microsoft needs to address these scenarios when they're pushing Windows 8 into the mobile space and especially when they're trying to bring your user account to the cloud.