AIUI, there are slight variations in the way different Zaurus distros present themselves when running usb networking; the "standard" way now is cdc_ether/g_ether; there are specific linux kernel build flags for these modules. I think there's some sort of NDIS driver for windows too.
I have no idea whether you can port the code to OpenSolaris at all; my guess is *maybe*, or you might find something in the OpenBSD tree which would help.
sorry to be so vague, I don't use usbnet any more, as I have CF adaptors for wifi, ether, bluetooth and GPRS, so I am quite spoiled for choice.
