What is the little circle located to the right of the ear-speaker on the HTC Inspire?

So on the front of the HTC Inspire, on the right hand side of the speaker that you put up to your ear when on the phone talking, there's a circle that looks like it should be the blinker for when you have text messages and such, but it's not. My friend told me it was the frontal camera, which later I found out it wasn't (unfortunately). So, now I'm just so curious to know what it is? Is it there with no purpose, or what?!