Anecdotally, I have run into this with Google Products (Mail & Voice): The "Archive" button is problematic because you can almost always navigate to the noun Archive folder, or verb Archive an item.
This is the proper approach, I suppose. I don't use images for button labels in Gmail's interface myself, but I'm pretty sure that properly designed icons + tooltips with verbs (for both icons and textual labels) can be used quite effectively to differentiate between verbs and nouns: 'arrows' icons as verbs for moving stuff, 'boxes' images as nouns for storage places, 'tools' as verbs for some particular actions associated with those particular tools, etc. - just your usual common sense UI stuff.
Switched Gmail settings to icons for buttons just to check if this is being used here and immediately notice annoying inconsistency in Gmail's UI: Archive button has an icon of a storage box with an arrow (good choice), but has ambiguous tooltip saying 'Archive', whilst Delete button has an icon of just a trash bin with a proper action-tooltip 'Delete'. 'Report spam' has the worst icon by far, I think. Then again - manila folder icon for moving to label (which is a bit unclear) - it acts very much like the 'archive' action, but somehow doesn't have an arrow. Labels button tooltip - 'Labels' - also lacks the word 'apply/attach/add'. I understand that you can get accustomed to almost anything, but this doesn't mean you have to fight your way through UI.
I thought a bit more about this and now I think that a verb is more or less mandatory for buttons of actions, i.e. for buttons that change some objects properties or performs actions on the objects ('Apply labels', 'Move to trash' are probably better than 'Labels', 'Trash'). Verbs are not mandatory for buttons that just change your position inside the system ('Go to inbox' is probably worse than 'Inbox').
Rather than the language used, perhaps the interface would give the proper contextual cue:
* Use a button interface for all actions the user can take: [send][archive].
* Use a link for nouns / places the user can go: inbox | archive | trash.
* Icons tend to be actions (a star for 'mark this as a favorite', a trash can for 'delete this thing', a paper+pencil for 'edit this entry'), so they get grouped more with the buttons.
