This would be interesting, I used a desktop app that instead of priority had a task, they ranged from possible to complete like:

possible, normal,
next,
current,
complete

It would be nice to have states for tasks other than complete and incomplete.

This would be very useful! I especially like the "state" idea.

I have always thought tags lent themselves to state metadata. You could have waiting, deferred, started, stalled, and on and on. You could then have a checklist to display tasks that lacked a state tag.

As for % complete, there are several here on the board who use the time estimate field for that purpose.

Yeah, but it seems natural that beetwen incomplete and complete a task could have other intermediate states that would not make sense once itś complete. A complete task could be ignored if it's marked as started, but it would seem like a workaround to have complete tasks in your started tag.

It would be a piece of cake to omit the completed tasks from the smartlists you use to view your states, so I don't think that would be an issue.

Just saying that the task status is in the same dimension as complete/incomplete.

Tags are ortogonal to the status one they are "meant" to group, give context and view tasks.

I still think it would be very usefull to have states other than complete/incomplete.

For example, it would be nice to see which of your task in your project smart list are inprogress, which are waiting, and wich were not started and still be able to sort by priority or due date.

Still wishful thinking...