Both iPad models (WiFi only and WiFi + 3G) have two WiFi antennas! Thanks to our friends over at the FCC we now know the iPad has got two WiFi antennas. It's not like the iPad will use both antennas at the same time: the iPad will just choose the one with the best reception. Another nice thing about this is that if one fails, you will still have a WiFi connection. Also, the iPad 3G is 0,3 milimetre higher and 0,1 milimetre wider than the WiFi-only model. The extra space is assumably needed because of the GPS chip and the 3G chip. The digital compass is included in both the WiFi-only and WiFi+3G models. It can also just be the plastic sticking out.