I installed the following Markdown-to-HTML converter by MacPorts.
py26-markdown @2.0 (python, textproc) Python implementation of Markdown
zsh: command not found: py26-markdown
How can you use py26-markdown?
You may need to explicitly call it from Python depending on whether it is executable by default or not.
To find out where the actual script lives you should ask port:
markdown.py doesn't necessarily need to be on your PATH, but it will be a lot easier to use it lives in your PYTHONPATH, which should include /opt/local/lib/python2.6/site-packages.
It's possible that your
Edit: Actually, wait, is py26-markdown even supposed to be a command? This page suggests it may be something you use from within Python.