It's either the most popular promontory in the world or a metaphor that's been exhausted in every conversation about economics since the election.But what does the fiscal cliff really mean, and what are local businesses doing, if anything, to prepare for it?In actuality, the cliff is a combination of automatic tax increases and spending cuts, estimated to be worth nearly half a trillion dollars, that will take effect in the new year if politicians can't reach a budget deal. It is the result of political gridlock from the fall of 2011, when a so-called super-committee cocked the hammers of deficit-reducing …