Verizon's Galaxy S3 — yes, that old salt — is getting an update today. And this update, apparently, gives the phone roaming access on Canada's Telus network. And ... well, that's it. You'll be up to Build JSS15J.I535VRUCNC1 with this one. So update at your leisure, if you're the kind who has to update all the things. (Like some of us around here.)
Source: Verizon support (pdf); Thanks to Ryan and everyone else who sent this in!