gistfile1.sh

# put this in ~/.bash_profile or whatever
python_or_python () {
  if [ "$1" == "" ]; then
    python
  else
    python "$@"
  fi
}
alias python="python_or_python"

gistfile2.txt

# now `python` on its own launches python
$ python -c "print 'hi'"
hi
$ python
Python 2.5.1 (r251:54863, Feb  6 2009, 19:02:12) 
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 'woot'
'woot'