There's been a lot of ballyhoo made over the iPhone 4's innovative antenna design and high resolution Retina Display, but you don't often hear too much about one of the unsung heroes of the handset's hardware, the gyroscope.

"A gyroscope, you say?" Yep it's in there, and it's a fine upgrade over the iPhone 3GS' compass and accelerometer hardware.

One of the areas where the technology will really shine, aside from gaming, is in the growing category of augmented reality (AR) applications. The folks over at ReadWriteWeb provide a great example of what throwing iPhone 4's gyroscope into the mix can do for an application. The video below shows an iPhone 3GS and an iPhone 4 running augmented reality app Accrossair side-by-side. The results are striking.

Seeing how much more usable an existing app can become with the inclusion of fresh tech in each new handset Cupertino unleashes on us is always encouraging, and speaks well to the types of features app store consumers can expect from their purchases down the road.