Should Mac menu items be title case? Should Mac menu items be title case? "New from Clipboard" vs "New From
  Clipboard"?


Gus Mueller asked this question on twitter and I am curious as well. If it is title case does it follow a particular set of rules such as the Chicago Manual of Style or Gruber's script? This would be especially good to know when writing scripts to activate menu options which are case sensitive IIRC.
With regard to that specific example, it's "New from Clipboard", as shown in the Preview.app File menu.

A cursory glance through some first-party menus shows that every word begins with a capital except articles, conjunctions and prepositions. There's nothing in the Menu Bar Menus section of the Human Interface Guidelines talking about the capitalisation.