Hi David,

Are you speaking of the last comment about subtasks with labels? If so, you can take advantage of the unlimited workspaces and dedicate an entire workspace to a project, using labels (and a clear naming and colour convention) to filter tasks and subtasks.

Project = iPhone App
Label = User Interface (colour choice)
Sub-task Label = SUB-UI (same colour, or different, whatever works for you to kill visual clutter)

That help?