Using the bus pirate to access the Chumby Hackerboard.

Physical connection:
  gnd to gnd
  MOSI to Rx
  MISO to Tx

Connection setup:
  Select mode "UART", 115200bps, Bits/Parity 8/none (default), a stop bit (default), default polarity, "normal" H=3.3V output (*not* default). Run the "Transparent UART bridge" macro (that's "(1)" on my bus pirate, other revisions may vary) for a typical interactive terminal - easiest to connect the bus pirate, set up the serial connection, then power up the chumby and watch it boot.