I bought a Linksprite Diamondback Arduino clone with onboard WiFi and found I couldn't upload a sketch over the USB connection. I'm using Ubuntu 10.04. After I plugged it in I was expecting the device /dev/ttyACM0 or /dev/ttyUSB0 to be defined but neither was available.
The problem was that the USB vendor/product codes associated with the onboard FTDI USB controller were not what the Linux driver was expecting.
This guy explains how to get around the problem:http://nattster.siamdev.net/2010/02/getting-a-ftdi-usb-to-serial-converter-to-work-on-ubuntu-9-10/
For the impatient:
1. Run 'lsusb' command to obtain the vendor/product codes, e.g.:
Bus 006 Device 005: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
2. Provide the vendor/product codes to the driver using 'modprobe', e.g.:
$ sudo modprobe ftdi_sio vendor=0x0403 product=0x6001
After these two steps the device /dev/ttyUSB0 shows up in the serial port list of Sketch, and uploads work as expected.