I've added the ability for PyConstraints to define a function (doDriver) that is able to directly modify values of the owner/target, so that certain setups can be created reliably. Users should take note that this is against the basic concept of what a constraint does, and that under no circumstances may they set the values of any variables controlling the transforms. For more details, check out the information in the PyConstraint template script.
I've also updated PyConstraints to be aware of geometry targets. The script template has been updated with this information.
Here is a script template for the "Script Templates" menu in the Text Editor. It provides you with the necessary functions for a PyConstraint set up, and also includes descriptions on what is required in each function.
