I think the bottleneck was mentioned to be the speed of (SPI) bus between OMAP and Wi-fi chip. You can't expect real G speeds with current Nokia tablets (practical maximum tends to be one half of 54Mbits i.e. something like 2.5MB/s) but still having G networking is very useful for battery life. With G speeds less time is spent on actual radio transmitting so the power is consumed for shorter time.