I thought this status was to indicate something had been pre-ordered or that the item had already been bought on a user's behalf but is not in one's collection just yet. A warning for potential secret santas that this game is already in the sleigh and another gift would be preferred.
This is what I use it for. Games that were on the list that I then bought but haven't received yet - usually because it was a pre-order and might take some time to arrive.
It also helps notify anyone who might have gotten it and had seen it higher on the list that it is now a no-go.