I don't know but entering the command:
>>> dir()
into the Python interpreter gives a list of defined classes and variables.
Using the TAB key on one of the existing objects opens a list of possible completions, i.e. its methods/attributes.
I'm not sure this is what the OP is asking. I think s/he's referring to the API documentation rather than the API itself. Calling help(object) in the interpreter is a good start for help on an object.
CL's answer: no, Python cannot introspect like Java; it can only do better.
wxPython
There is, however, such documentation for wxPython (a GUI-building kit for Python), although it is still under development. [http://www.wxpython.org/docs/api/ Here is the link].