In OS2008 there's a driver for the Realtek 8150 chipset, so I'd imagine it's at least possible to use adapters based on it, provided you can power them.

It should be possible to compile kernel modules to support other chipsets as well.

As far as I know the USB port only provides 100mA of current, which isn't enough for most devices. I grabbed an adapter off eBay, once I get my hands on it I'll be doing all I can to make it work