On the recommendation of a friend, I picked up 7 Wonders, and two other friends and I played our first game a few nights ago. When one of my friends played Vineyard, we had a lengthy discussion of what the rules meant.
The card is worth 1 coin per brown card built in the player's city AND in the two neighboring cities.
Clarification: The brown cards built on in the neighboring cities on the same turn as the Vineyard are counted.
Emphasis mine. The key discussion is what is meant by built. In this context, it's ambiguous as to whether "built" is in the past tense or the future tense. During our first game, we came to the conclusion that it must mean future. We arrived at this conclusion through the misconception that the players would be paying the Vineyard owner instead of the owner drawing the funds from the central bank. By the second game, we had forgotten our misconception, and decided that built must be past tense, as there are far too few resource cards in the second age, and none in the third, to make Vineyard worth while. We didn't really worry about it that much, since I discarded Vineyard on the last turn.
So, what is actually meant? Do I collect a coin for every brown card I have in play right now, as well as a coin for the brown cards my neighbors have in play at the end of this turn? Do I disregard existing brown cards, and collect a coin when my neighbors or I play a new brown card? Or is it everything - do I instantly collect a coin for existing brown cards, as well as a coin for each future brown cards when they're played?