The JythonMap behaves the same as a dict for most purposes.
If you look at the reference above, you'll see it supports all the usual methods of a python dict, including keys(), items(), etc.
On closer inspection, there is also a toDict() method that presumably will explicitly return the dict inside the wrapper. However, you should never really need it in everyday usage.
See also the discussion here:
EDIT: updated javadocs reference to latest version (as of this posting)