UK iPhone app developer Essency Limited has announced that V2.4 of Awareness! The Headphone App will be free for 2 days, until the 1st of January 2012. Awareness! is a unique app that allows headphone users to hear what’s going on around them while listening to music (or any other audio) on iPhone, iPad, or iPod touch. With Awareness! you can hear when the person next to you talks, or if out walking or cycling, when a car or truck blows its horn. This app usually retails for $6.99/£4.99 – Click here to download for free. Awareness! is a unique app that allows headphone users to hear what’s going on…