I think the Cubietruck has it (along with a SATA port), never used one though: http://www.cubietruck.com/collections/frontpage/products/cub...

Also worth checking that the hw is good enough to fill a gigabit connection. Many of the cheaper machines (for instance, the WD MyBook World, like in the article) cannot really sustain gigabit disk<->network transfers. The limiting factor is often the CPU or a slow bus connecting the NIC, hard drive and CPU.

Some hardware (such as the raspberry pi) has its network speed limited by the usb network adaptor.

Yup. Utilite: http://utilite-computer.com/web/utilite-specifications. Dual GbE, though one is limited to around 470Mbps because of a limitation of the board.

I have one. Great specs, but I am not totally happy with the ubuntu 12.04 that comes with it. GCC is broken, for one thing: http://www.utilite-computer.com/forum/viewtopic.php?f=64&t=1.... Hoping this gets fixed soon.

I'm not using my ARM board as a media server or content renderer, just as an edge gateway much like the OP is.

The OP is "sharing media files with Samba to an Android tablet", but if you really need >100mbit to do that, I don't know what to tell you. I'm puzzled by everyone that wants to grind every random cheap SoC into a media server.

Some of these have gigabit ethernet and are pretty cheap

https://wiki.debian.org/FreedomBox/TargetedHardware

I learnt about the IFC6410 board in this thread which seems to have real gigE rather than gigE-via-USB like many other single board computers.

Cubieboard 3 (aka Cubietruck) will do 1gbit as well as 1 sata port.