Twitter announced keyword targeting for its promoted tweets today, adding to its existing geolocation, mobile device, and user interests filters and further expanding the functionality of its growing ads network. The microblogging site has already carried out limited trials of the new feature, with advertisers including Walgreens and GoPro reporting engagement levels as high as 11%.

The keyword targeting feature has been billed as a game changer, and presents an exciting opportunity for advertisers to target users' off-the-cuff remarks, catching their interest before they have even reached the search stage of the purchase cycle. Combined with Twitter's other search parameters, this new feature allows marketers to reach highly qualified customers in real time.

Read the full announcement on the Twitter Advertising Blog.