I would assume that, in common with most Ethernet cards, lit up means high speed. But it could be dual-colour in principle.
The datasheet says that it is open-drain and driven low when operating at 100Mbps. Unless the foundation have wasted space and components to convert it to a driven high-level output, the LED is on when linked at 100Mbps.
That was my guess too, some cards do dual-colour too (usually for Gbit), I'll assume they kept it simple (pointless adding extras for no reason) and the 10M label should really be "100", no biggie as I doubt most would even notice if it was there or not. I would also guess they are not populated for model A.
If there are any changes then we can update in the wiki. Thanks for working out the info.
I'll also add something about the Auto-MDIX on the LAN so you don't need crossover cables.
(I'm hoping this will mean a nice easy way to connect to a laptop and vnc directly - even if it is through a usb-lan dongle on the laptop).
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