Sadly the rk3188 on-chip controller is only capable of 100mbit. There's a few more (particularly Freescale) units with gigabit, but generally more expensive. Gigabit or USB3 is when these things start to look insanely attractive IMHO (as possibilities to attach e.g. storage to the external bus exist)
The imx6 onboard Ethernet can't really do gigabit but the second Ethernet on this new machine is apparently a PCIe connected Intel chip which is more promising.
