Fortunately, CultofMac notes that the “Save As…” is due to make a triumphant return on Mountain Lion, although not in quite the way you might remember it. Instead of adding the command back into the menu bar, Apple has re-enabled the command through a new keyboard shortcut: Command-Shift-Option-S.
Considering that the command was mostly only missed by long-time Apple owners and power users, however, bringing back “Save As…” in command form only actually seems to make a lot of sense. Personally, I’m just glad it’s back, regardless of which form it takes!