I live in West Tennessee and my weather and map shows me in Yerevan, Armenia. This only happens when I am at home. My wife's 4 does the same. I have the 4s. This started happening when I upgraded to 5.0.
If you go into your weather app and press the small i at the bottom right of the screen you can toggle show local weather. This seems to be set to off by default with ios5.0.1 update for whatever reason. Hope this helps.