Ah, I see... I did read that some region-based apps/downloads, etc. could have issues, and changing region isn't as trivial as I would have first expected.
If you only set up USA for the language or keyboard, though, you can change most of those settings under the "Language & input" area of "Settings". Nothing for the base, hardware default region that I can see, but that is where you can set up on-screen language, keyboard type, dictionaries, etc...
When the ICS update comes out in a few days (a little later for Canada, though maybe the USA setting will gain you a few days *smile*), there might be more settings or the chance to re-enter region info -- not sure. Current information says the US push of ICS (Android 4.0.x) will start on April 27th and on May 3 in Canada. Looking forward to it, especially the new Chrome browser and ability to create desktop folder/groups!