When I start python-shell (or even just start python from M-x shell), Emacs gives the expected prompt:
bash-3.2$ python
Python 2.7.1 (r271:86832, Jun 16 2011, 16:59:05)
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
But when I type something at the prompt and press RET, the cursor moves down a line but the command is not executed. The only commands I can get the subprocess to respond to are interrupts like C-C C-c. After an interrupt, another prompt (>>>) appears and I can use M-n and M-p to navigate the lines I "entered" earlier.
>>> test
hmmm, definitely pressed enter there
C-c C-c
KeyboardInterrupt
>>>
Curiously, this occurs both in Aquaemacs and in emacs -nw. I've tried moving my .emacs and .emacs.d files and the behavior is the same. Any ideas on what might be causing this?