What does "s-[keyname]" refer to in Emacs, and how do I tell Emacs to ignore it?

Question

Background information:

I'm on a Mac, and I've just upgraded to Emacs 23.1 via http://emacsformacosx.com/. There are a few issues, notably the lack of full screen ability.

I've attempted to get around this last issue by installing Megazoomer, which adds a global input manager bound to Cmd-return. This causes the currently forward application to maximise. However, Emacs reports that <s-return> is undefined. I've never seen an s-[key] mentioned before, and Google isn't forthcoming with an answer.

So, two parts:

1. What does s-[key] mean? This is purely for my satisfaction; and
2. Can I tell Emacs to ignore this key combination and let the key combination carry through to the system (so that hopefully I can have full screen Emacs back again)?

EDIT: so 1) is resolved, and as to 2) I've got: (global-set-key (kbd "<s-return>") 'ignore), which at least stops the error. However, Emacs still swallows the key combination, which isn't ideal.

Answer 1

(setq ns-command-modifier nil)

That is supposed to do what you want. However, it's having somewhat unpredictable behaviour on machine when I test it, so be warned.