Are Facebook and Farmville Developer Zynga in a Standoff?

Zynga, makers of feed-cluttering, endless-status-update-generating agribusiness simulator Farmville, is one of the biggest and most prominent Facebook developers. But that doesn't mean they get along. Their relationship as of late has been described as "intense" and brittle, and it seems to stem from Facebook's recent move into unified credits.

The credit system, in which all in-game purchases must be conducted in FaceBucks (patent pending on that winner of a pun, Zuckerberg) instead of real...