WPILib has an ultrasonic sensor implementation that you may find useful:
http://robotpy.readthedocs.org/en/la...ltrasonic.html
Once you get the distance data, you can send it to SmartDashboard as mentioned earlier --
wpilib.SmartDashboard.putNumber().
Running SmartDashboard/SFX is pretty simple, and is great for viewing the raw values that the robot sends back. However, if you want to do something with the values, you shouldn't use SmartDashboard/SFX (unless you want to write a SmartDashboard/SFX extension in java).
If you want to write your own networktables client (for example, your wxpython program) to talk to the robot, and receive values from the robot, check out pynetworktables. What you would do is import networktables, get the SmartDashboard table, and ask for the values. You can also get notifications when new data values are sent by the robot, for easier usage.
There's an example
here and
here.