Twitter has added a new feature that can make the service more relevant. In the right-hand navigation bar, under "Trending," you can now select a geographic region to see what's hot on Twitter in one of a few cities.
Only 15 U.S. cities and five non-U.S. countries are on the locality list, although it's very likely that Twitter will add more locations shortly.
Twitter last year rolled out a geolocation API, which lets posts from Twitter apps--but not the Twitter.com site--tag each Tweet with the location where it was made. Presumably,Twitter posts from the site itself inherit their users' static location from their profile page.
This new feature is a nice fillip on Twitter, but it could be better. If it automatically located you, so you always got what was happening around you instead of what you said your home city was, it might be a very valuable ad-hoc guide to wherever you're opening your laptop. That would require the browser return you location. HTML 5 has geolocation reporting, but support for HTML 5 is only beginning to roll out. Fortunately, some mobile Twitter apps, like TweetDeck, already allow you to see Tweets that are geo-tagged as near you. Also, Twitter would be wise to put this feature on the Twitter.com pre-sign-in home page, to make it more clear to new users what Twitter has to offer them.