GadgetsDNA (via MacRumors) reports that a radical new design is in the works for iPhone 5 which is somewhat inspired by the iPod touch.  Machine translated:

We’re a bit skeptical of this report.  While Wifi and GPS antennas could shoot out the Apple logo in the back, such a design wouldn’t be great for 3G reception, something that is a high priority for Apple.

Antenna will be designed just behind Apple Logo so that cellular and Wi-Fi signal can penetrate easily. Side exposed steel antennas seem to be abandoned, as designed in iPhone 4.

Mockup above provided by Macotakara