Though it began as a platform for broadcasting the answer to the question “What are you doing?” in 140 characters or less, Twitter has become so much more.

As a tool for self-promotion and marketing, it has rejuvenated careers. Just ask Shaq.

As a tool for citizen journalists (read: everybody) it has become an invaluable source of real-time news. (Hence the change last year of the question from “What are you doing?” to “What’s happening?”)

And for business as well as daily life, Twitter has become an invaluable tool for networking, marketing and finding out what’s going on in the wider world

Now, with the local trends feature that the microblogging service just rolled out, Twitter is becoming more relevant to its users in a local context.

So far, only about seven countries and a dozen or so cities are being tracked, but that will of course expand. As of now, our home base of Kansas City isn’t on the list — a surprise to no one here in this cowtown.

But when it does roll out everywhere, expect Twitter’s local trends to change the way you do business and, frankly, conduct your life.

Here are the three main ramifications:

1. Communication: By being able to see what people in your area are talking about, it will be easier to join conversations and network.

2. News: People seeking news about a major local event, such as an election or (*gulp*) disaster, will now be able to get pertinent information faster, without having to wade through what the rest of the web has to say about similar topics. Or wait for local professional news outlets to report it.

3. Business: Marketers will be able to use local trends to target their messages based on topics that are popular in their community. Businesses looking to develop or introduce new products can base their decisions on what people are most excited about.

Those are the broad strokes, of course. If we’ve missed any big ones, let us know.

Also, in what more specific scenarios could Twitter’s local trends be useful?