Enable suport for explicit task status

I don't know much about GTD, but one concept that I use is task status. I guess you could use tags for this, but I think it would really help if GTG had explicit task status support.

The statuses that I use are: next, ready, waiting and someday; but I think it would be best if they were customizable.

Finally the statuses could have colors and numeric keyboard shortcuts assigned to them, much like thunderbird tags (0~5).