I know of python -c '<code>', but I'm wondering if there's a more elegant python equivalent to perl -pi -e '<code>'. I still use it quite a bit for things like find and replace in a whole directory (perl -pi -e s/foo/bar/g * or even find . | xargs perl -pi -e s/foo/bar/g for sub-directories).
I actually feel that that which makes Perl Perl (free form Tim Toady-ness) is what makes perl -pi -e work so well, while with Python you'd have to do something along the lines of importing the re module, creating an re instance and then capture stdin, but maybe there's a Python shortcut that does all that and I missed it (sorely missed it)...
The command line usage from 'python -h' certainly strongly suggests there is no such equivalent. Perl tends to make extensive use of '$_' (your examples make implicit use of it), and I don't think Python supports any similar concept, thereby making Python equivalents of the Perl one-liners much harder.