One of the many speculations about the new iPhone 6 says that the logo Apple it will light up on the back side. The leaked back covers, on which a hole for the logo was cut out, should have indicated this Apple, but it is possible that this logo will simply be glass. There is no evidence that it would Apple indeed he planned to use an illuminated logo, but there is ample evidence that the logo will be glass, and there will be an antenna under the glass, unless it is just an aesthetic element.
Speculation was most recently fueled by a photograph of the company's logo Apple it has a plastic body. According to the originator, the object, which should fill the logo on the back of the phone in its final form, is transparent enough for light to pass through it. This would mean that the logo would flash if users received a phone call, received an SMS or received an e-mail. But there is no danger, as numerous evidences indicate that the logo will serve as an antenna, just like on the iPad. Apple because he wants the rear cover to be made of aluminum as much as possible, but aluminum is not the best material for signal transmission.
Offtopic: it came out iOS beta 4