It's a fairly painless process to update your location. They let you enter ICBM coords, zip code, major city, or just click on the map image. To verify your identity, they ask you to temporarily add an item to your "interests" LJ list.
...You can also tell who just clicked their approximate location on the unzoomed map as some of the dots are not precisely where people are. And then there's Brokken's dot. :)