[nfriedly]

Comparing the photos to my Pi 2, it doesn't seem very different. There's an extra IC near the microsd card, a connector beneath the HDMI port, and a few other small changes.

But nothing that looks like an antenna. Any idea where that might be?

Edit: as lovelearning pointed out, there is a small ceramic-looking piece in the upper-left of the top side, near the GPIO pins and LVDS display connector. That might be it.

[casylum]

Look for a cutaway ground plane as a hint to where the antenna may be.

http://imgur.com/a/z9bDR

Wifi antenna and chip set highlighted.

[Squonk42]

That is it, and the connector beneath the HDMI port is the same (but mounted) JTAG connector as the RPi2.

I don't know what is the chip, though.

Also noticed a 2-pin header between the 40-pin one and the upper USB ones: it looks like the "RUN" from the Rpi Zero.

EDIT: The 2-pin "RUN" header already existed on the RPi2, where the ceramic antenna is now located on the RPi3.

[Squonk42]

There is a big Diode D5 near the micro-USB power connector.

[nfriedly]

Also worth noting: the new IC and the suspected ceramic antenna are in about the same place on opposite sides of the pcb. So I think that lends some credence to the idea that is is an antenna.

Man they can make small antennas these days...

[agumonkey]

First thing that came to mind. All the wifi ready SBC have a very easy to spot chip and some form of visible antenna. I'm almost thinking the shots were just for gross form factor approximation.

[agumonkey]

Here's a Xray shot, https://twitter.com/oliverquinlan/status/704701651005915136/...

antenna : checked

[bravo22]

According to FCC report they are using a chip antenna.

[oxplot]

Second last "internal" photo, top left corner next to the ribbon connector. That thing that looks like a long cap SMD is the chip antenna (just guessing).