(as of this morning, 9th August, 2008)
I tried to save hold a story for Samzenpus as a possible for the Idle section, but find that it does not drop out of the hose.
Process:
From all-stories-collapsed view of the hose, I clicked on the title to expand the story.
I added "idle" as a tag.
I clicked on "submission" to get the drop-down menu including "hold," and selected "hold."
I clicked the title to collapse the story, and expected it to disappear from the hose shortly. This didn't happen, so I tried again, in case it was just that my mouse slipped and "hold" never got selected. However, same result -- the story remains in the hose.