On Windows the --enable-apps option can be added to the start menu shortcut of Chrome. On Mac OS X, you need to create a small shell script inside the Chrome bundle:
#!/bin/sh exec "$0.bin" --enable-apps $@
Note that the same principle can be used to add command line options to any Mac OS X application. You may have to do this again after Chrome has been updated.
Now you can play with it and install the Hacker News application or my own kfalck.net application. They basically just add web shortcuts to Chrome's application menu. You can view the menu by pressing Command-T (or Ctrl-T on Windows/Linux).