We have just renamed projects to lists on both the web and iPhone apps. While this won't affect your workflow, we thought it best to explain what may seem like a trivial change.
One of our driving philosophies with Flow is workflow agnosticism. Our goal is to provide a simple toolset, which can be adapted to anyone's workflow rather than imposing a specific methodology like GTD or Agile. Such methodologies get in the way of true and open collaboration and present participants with an immediate learning curve.
A project is a task list with a clear, definitive goal: "Implement New Feature", "Create Marketing Video", "Organize Wedding Reception", etc. A list is simply a collection of—often related—items, and in Flow's case, a list of tasks. At MetaLab we keep ongoing lists of bugs, feature ideas, and general office tasks. None of these lists have a goal and will never really be completed. Personally, I keep general chore, shopping, and grocery lists. Clearly, these will never be completed either.
Finally, we've renamed list completion to list archiving to again remove the implication that lists are meant to be completed upon reaching a predetermined goal. So from now on, you will create task lists and archive them when they are no longer useful.