In the IGN preview, they wrote that you don't direct the culture towards hexes. It's differentiated automatically towards places where people are more inclined to settle down. You can invest in tiles to speed up the process for that tile, though, but as I understood it you use gold for that.
So I'm guessing there still is a culture level for each city, in addition to some kind of empire wide culture.
Yeah, I read the IGN preview after posting.
But why does this necessarily imply a localized city culture?
I could see an empire-wide culture working, with each X culture earned buying a new tile somewhere in the empire, favoring tiles that are on better terrain, and favornig tiles that are closer to your cities (so that a new city will tend to expand to its 2nd ring before an old city expands to its 4th ring). You could also just spend Y gold to buy an extra tile somewhere (you don't pick the tile, it could be picked on the same random basis.
Local *and* global culture seems like it would be confusing, and the screenshot seems to imply global culture.
* * *
I'm betting that one of the big reasons that they're doing the culture system as they are (flatlands covered faster) is to encourage more "natural" national borders. Most national borders are along natural boundaries; rivers or mountain chains. Exception obviously for post-colonial boundaries drawn by arbitrary lines on a map (US/Canada, Africa, etc.).
This will also obviously have military implications, because with impassible mountains and 1upT it is going to be much harder to invade through mountain passes, so controlling the difficult terrain culturally will give a big tactical advantage (and having those areas on the borders will make invasions more difficult).
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Economics or something else. While the happy face is referring to some kind of diplomatic situation. Especially as it's grouped with culture and research. These are just wild speculations though, and I almost expect them to be wrong 
