I was just reading the Wind cite and they are real interesting (if I was a Cannuck). First, when I first read about "home zones" on Wind's website, I thought that they were talking about a regional market like the competitors. (E.g. Toronto zone, Vancouver zone, Calgary zone, etc). They aren't, they are talking about "on network." A Toronto Wind phone roaming in Vancouver is on network. Away zone is roaming on other people's network and that is $0.25 a minute. The exception is their $35 "Always talk" plan which is province wide/home zone.
WIND Mobile | Support | FAQs
Wind will roam in the U.S. at $0.25 a minute. On network, you can get 5 gigs of on-device data for $35. It will be interesting to see what their tethering enforcement will be.