The github style of software development has, unusually, embraced the "fork" as a way of encouraging software use and reuse. Rather than being tied to a single repository owned by a single maintainer who accepts or rejects patches at their whims, you can easily fork an entire project in github and then work on it on your own. Notably this is not seen as treasonous even if it means that plans diverge.
Github is mostly about software, but there are lots of other things that lend themselves to incremental parallel development - development that doesn't have to follow the wiki model of last one in gets to edit. If you think of github (the hosting service) combined with some shared recipe archive (a la grouprecipes, the Usenet Cookbook, or whatever your favorite recipe starting place is) you're thinking about what I'm thinking.
Lots of people cook the way you'd expect, starting off from a given recipe and then branching out to accomodate the seasons, ingredients on hand, their own tastes and the tastes (picky) of their family. If I'm doing a cookbook, I want to acknowledge that someone else's mac and cheese recipe was the starter of my own but I don't want to actually edit their cookbook in writing mine.
Besides, "fork" is such an obvious name for a cookbook tool.
