Yep- as Oz said. Needs to be worked to gain anything from it, like every tile...
How exactly does a person work a Natural Wonder tile, which by default cannot be altered?
Aside from waiting for the governor to automatically choose it, you set it manually by opening up the citizen management panel, and then selecting the tile you want to work. As Oz said though, it provides no food, so the only growth tile will be your capital, unless you already have a greater pop than 1/2.
EDIT: Unless you're asking in regards to a worker, no they don't work it, your city manager will.
friendly warmonger.
It always surprises me how many new players don't know how to allocate citizens. Like in CIv4 or SMAC, as soon as you click a city, you had big circles or big icons superimposed on top of tiles, and it was clear that you could shift them around. Every time you load up CIv5, you need to click a tiny little icon in the top right corner of the screen before it lets you start shifting citizens around. That's some terrible UI design.