It would certainly be very difficult. If you could get the bus noise near the 2.4GHz freq range (unlikely), you could use the wifi of the other computer to potentially receive.

Another thing people have experimented with is using the speaker/microphone at above human hearing range. This method usually falls flat because crappy laptop speakers have a hard time going above 20kHz.

One thing I could potentially see working is a laptop with a hard drive generating vibrations with the motor. Then, a smartphone or laptop with an accelerometer could pick up the signal using the coupling through a table.