When unhandled in python code exception occurs in PyObject_CallMethod 
frame_dealloc() (Objects/frameobject.c:422) 
not called. Even if I call PyErr_Print(). 

But if I call PyErr_Clear() then all okay. Documentation says that both 
this functions doing same work(http://docs.python.org/3.0/c-api/
exceptions.html). As we see thats not true or not all nuances documented.

Examples and more on this mailing list:
http://groups.google.com/group/comp.lang.python/browse_thread/
thread/19316b3effa37d2d

I think I have an explanation:
When a python exception is raised, the current call stack is stored in
the exception state (tstate->curexc_traceback). This includes all the
living frame objects, with all their local variables.
This explains why frame_dealloc is not called at this time, and why the
"self" object has its refcount increased.

PyErr_Clear() releases everything.
PyErr_Print() does clear tstate->curexc_traceback, but only to copy the
value into sys.last_traceback; So the frame object is still alive.

I suggest you to use PyErr_PrintEx(0), which will print and clear the
error, but not store the exception info into the sys.last_* variables.
[PyErr_Print() simply calls PyErr_PrintEx(1); No, it's not yet documented]

Thank you for your activity. This feature drank alot of my blood. Please 
document this or change behavior.

PS Older python versions may be also affected so changing behavior may 
brake existing code :(

Documented PyErr_PrintEx() in r69292.