It's a myth that Coca-Cola is a closely held secret, though. Any food flavoring specialist can reconstruct the flavor of Coke almost exactly.

A few years ago I (not a specialist!) made lots of batches of OpenCola, which is based partly on the original Pemberton recipe, and it comes so close that nobody could realistically tell the difference. If anything, it tastes better, because I imagine Coke doesn't use fresh, expensive essential oils (like neroli) for everything.

The tricky piece that nobody else can do is the caffeine (edit: de-cocainized coca leaf extract) derived from coca leaves. Only Coke has the license to do this, and from what I gather, a tiny, tiny bit of the flavour does come from that.