Great plugin. I'm using it across a large network of blogs and it makes scheduling feed articles really easy.
I saw one comment from angelamarie from 6 months ago where she asked for a slush pile. You had said that not having the articles show up on the calendar made editing problematic. All I would add to that conversation is, I don't mind if it is still shows up on the calendar in DRAFT status. There just needs to be a box that lists all the unpublished posts, from which they can be dragged and dropped onto the calendar.
The other feature that would be great is a view option. Three weeks is too small a window. I'd like the option to be able to open it up to four, possibly five, weeks.