Twitter quietly rolled out a new feature today that enables users to choose a regional preference for viewing trending topics.

Called Twitter Local Trends, the new functionality gives users the option to set their regional location and view trending topics happening in their part of the world. For example, one of the screenshots pictured shows that the topic “Trafalgar Square” is trending for users that have United Kingdom set as their region (because it relates to a well known London icon), but not for users that have set their region to Worldwide.

At this stage, only seven countries and 15 cities in the US are available for selection (see screenshot below) but more will be added soon.

According to a post on Mashable, the feature has only rolled out to around 1 percent of Twitter users, but there’s nothing official on the Twitter Blog about it yet. I noticed it in my account this afternoon so I’m not sure if I’m part of the lucky 1 percent or whether it has rolled out to a larger audience since it went live this morning.

Regardless, when it does roll out to everyone, it will make a huge difference to how we use Twitter to target a regional audience. The benefits for geo-based mobile apps like Four Square and Gowalla should be immediately apparent. Add to that the ability to pinpoint regional trends in real time search and this becomes a social media game changer.

Everybody knows a business that is still sceptical about using Twitter. But when they see they have the power to follow and influence social media conversation in their specific target markets using Local Trends, I think even the sceptics could be convinced to start using Twitter as a full time marketing channel.

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