Google Maps always shows me distance values for direction results / navigation in miles, although it does show me a scale on the map itself in metric units. I rather prefer to get my direction distances in metres/kilometres. Is there any way to achieve this in Google Maps? I searched a bit for this and suggestions seem to be to change locale in Settings > Language and Keyboard. Mine is currently set to English UK.
I'm in Canada and recently made a road trip to the states. When I'm planning a trip starting in Canada, the whole trip is in km, even if it crosses into the US. If the trip starts in the US, however, it shows everything in miles, even if it crosses into Canada. It appears that it's not the location set in your phone but rather the location of the phone itself (if using "my location" as the departure point - otherwise it's just the departure point).
You can try this out by plotting a trip from a "miles" country to a "km" country and then clicking the reverse trip. The units changed with me.
Unfortunately, I saw no way to post a comment to your question though this is not really an answer:
I am spanish and therefore my Samsung Galaxy Tab is configured for my country. When using the measure ruler from the labs tab of Google maps I get all the distances in metres/kilometres instead of miles.
So it seems that changing the locale might help